Search

As a key component of cell-cultured fish, fish skin gelatin (FSG)-based cell scaffold provides support structures for cell growth, proliferation, and differentiation. However, there are potential allergenicity risks contained in FSG-based scaffolds. In this study, 3D edible scaffolds were prepared by phase separation method and showed a contact angle of less than 90°, which indicated that the scaffolds were favorable for cell adhesion. Besides, the swelling ratio was greater than 200%, implying a great potential to support cell growth. The sequence homology analysis indicated that FSG was prone to cross-reaction with collagen analogues. Additionally, a food allergic model was constructed and represented that mice gavaged with cod FSG exhibited higher levels of specific antibodies, mast cell degranulation, vascular permeability, and intestinal barrier impairment than those gavaged with pangasius and tilapias FSG. Its higher allergenicity might be attributed to a higher number of digestion-resistant linear epitopes. Moreover, the higher hydrolysis degree linked to the exposure of linear epitopes to promote the combination with IgE, which was also responsible for maintaining the higher allergenicity of cod FSG. This study clarifies allergenic risks in cell-cultured fish and further study will focus on the allergenicity reduction of FSG-based cell scaffolds.

The objective of the present work was to evaluate the efficacy of a novel antigen carrier using mannosylated gelatin nanoparticles with entrapped inactivated porcine reproductive and respiratory syndrome virus (PRRSV) in inducing T cell mediated immunity in vitro. Gelatin nanoparticles (GNP) were modified with mannose to form mannosylated gelatin nanoparticles (MnGNP), which can efficiently and specifically target monocyte derived dendritic cells (MoDCs). The inactivated PRRSV was encapsulated in the MnGNP and GNP, referred to as MnGNP-PRRSV and GNP-PRRSV, respectively. All these prepared nanometer particles were characterized for size, surface charge, drug encapsulation efficiency, and drug release. The efficacy of MnGNP in targeting MoDCs was investigated, as well as the subsequent MoDCs maturation and T cell mediated cytotoxicity. The developed MnGNP-PRRSV particle was characterized with a nanometric size of 302.67 ± 3.2 nm, surface charge of 23.81 ± 1.26 mV, and PRRSV encapsulation efficiency of 63.2 ± 1.85 %. The maximum uptake of MnGNP in MoDCs in vitro was 15.5 times higher than GNP with a shorter reaction time that peaked 4 h earlier. The uptake of MnGNP-PRRSV induced maturation of MoDCs and significantly enhanced expression of SWC-3a, CD80, CD1, SLA I, SLA II on MoDCs, compared to PRRSV (p < 0.001). The cytokine secretion of IL-1β, IL-6, IL-10, and IL-12 was also increased in MoDCs when treated with MnGNP-PRRSV, compared to PRRSV (p < 0.05). The matured MoDCs triggered T lymphocytes in autologous peripheral blood mononuclear cells (PBMCs) activation, proliferation, and differentiation into effector cytotoxic T lymphocyte, suggesting increased amount of activated T cells after MnGNP-PRRSV treatment. Additionally, the function of T cells to kill PRRSV infected cells was 83.98 ± 2.62 % when triggered by MnGNP-PRRSV, compared to 60 ± 4.7 % in PRRSV group (p < 0.001). These results indicate that MnGNP with entrapped inactivated PRRSV can effectively and specifically target dendritic cells for maturation and activation, and subsequently improve T cell activation, proliferation and function to kill PRRSV infected cells., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Objective: To assess the iatrogenic risks of gelatin allergy and identify resources for patient management., Data Sources: A literature review was performed using PubMed and public databases provided by the National Library of Medicine., Study Selections: Reports of iatrogenic gelatin allergy associated with vaccines, hemostatic agents, intravenous colloids, medicinal capsules, and intraoperative surgical supplies., Results: Gelatin ingredients may not be identified by electronic medical record safeguards, and an exhaustive listing of potential iatrogenic exposures is elusive. The National Library of Medicine AccessGUDID (https://accessgudid.nlm.nih.gov/) can be a useful resource in evaluating medical devices for gelatin content. Unexpected sources of iatrogenic gelatin exposure include hemostatic agents, vascular grafts, intravascular cannulas, bone replacement implants, and emergency resuscitation fluids., Conclusion: Vigilance is important within medical systems to avoid inadvertent gelatin exposure when caring for patients with gelatin allergy. Additional safeguards are needed to remove latent health care system errors that fail to prevent gelatin administration in this at-risk population., (Copyright © 2019 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Objectives: Compare the effects on inflammatory (TNF-α, IL-6, IL-8 and IL-10) and immunologic (CD3(+), CD4(+), CD8(+), CD11b(+), CD16(+)/56(+) T cells and total lymphocyte concentration) variables of hydroxyethyl starch 130/0.4, 4% modified fluid gelatin, or crystalloid when used as volume replacement fluids for acute normovolemic hemodilution (a blood conservation technique) in coronary artery bypass graft patients., Methods: Thirty patients undergoing coronary artery bypass graft surgery were randomized to receive Isolyte S® (Group ISO), 6% hydroxyethyl starch 130/0.4 (Group HES) or 4% modified gelatin solution (Group GEL) for acute normovolemic hemodilution. Blood samples were taken immediately after induction of anaesthesia (T0), and 2 h (T1), 12 h (T2), 24 h (T3), and 48 h (T4) after separation from cardiopulmonary bypass. TNF-α, IL-6, IL-8 and IL-10 levels were determined with commercially available ELISA kits. CD3(+) (mature T cells), CD4(+) (T helper cells), CD8(+) (suppressor cytotoxic T cells), CD16(+)/56(+) (natural killer lymphocytes), and CD11b(+) (Mac-1, adhesion receptor) levels were measured using flow-cytometry reagents. The CD4(+):CD8(+) ratio was calculated., Results: Between-group comparisons showed significantly higher levels of TNF-α at T1 (2 h after weaning from cardiopulmonary bypass) in Group HES compared to Group ISO (p=0.003). IL-8 was significantly lower in Group HES than Group GEL at T1 (p=0.0005). IL-10 was significantly higher in Group HES than in Group GEL at T1 (p=0.0001). The CD4(+):CD8(+) ratio in Group ISO was significantly lower than that in Group HES at T2 (p=0.003). CD11b(+) levels in Group HES were also higher than those in Group GEL and group ISO at T2, but not significantly. CD16/56(+) levels in Group HES were higher than those in Group GEL at T2 (p<0.003). No excessive hemorrhage occurred in any patient. Mediastinal drainage during the first 24 h after surgery in Group HES (347±207 mL) was not significantly different from that of Group GEL (272±177 mL) or Group ISO (247±109) (p>0.05)., Conclusion: Hydroxyethyl starch 130/0.4 reduced pro-inflammatory responses and increased anti-inflammatory responses to a greater degree than gelatin solution and isolyte S®. The use of hydroxyethyl starch, compared to gelatin solution and isolyte S®, resulted in less decrease in the CD4(+):CD8(+) ratio, suggesting less immunosuppression., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Hydrogels prepared from gelatin and lysine diisocyanate ethyl ester provide tailorable elastic properties and degradation behavior. Their interaction with human aortic endothelial cells (HAEC) as well as human macrophages (Mɸ) and granulocytes (Gɸ) were explored. The experiments revealed a good biocompatibility, appropriate cell adhesion, and cell infiltration. Direct contact to hydrogels, but not contact to hydrolytic or enzymatic hydrogel degradation products, resulted in enhanced cyclooxygenase-2 (COX-2) expression in all cell types, indicating a weak inflammatory activation in vitro. Only Mɸ altered their cytokine secretion profile after direct hydrogel contact, indicating a comparably pronounced inflammatory activation. On the other hand, in HAEC the expression of tight junction proteins, as well as cytokine and matrix metalloproteinase secretion were not influenced by the hydrogels, suggesting a maintained endothelial cell function. This was in line with the finding that in HAEC increased thrombomodulin synthesis but no thrombomodulin membrane shedding occurred. First in vivo data obtained after subcutaneous implantation of the materials in immunocompetent mice revealed good integration of implants in the surrounding tissue, no progredient fibrous capsule formation, and no inflammatory tissue reaction in vivo. Overall, the study demonstrates the potential of gelatin-based hydrogels for temporal replacement and functional regeneration of damaged soft tissue., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

We report here a 20-year old woman who referred to our clinic for identify the responsible antigen of anaphylaxis. Five days before the reaction, she had a cold and had taken a gel capsule cold medicine, Stona IB Gel®. On the day of the reaction, she took a dose of Stona IB Gel® after eating yogurt. Five minutes after oral administration, she developed a heat sensation and pruritus on her neck, with flushing, abdominal pains, breathing difficulties, and syncope. The specific IgE antibodies measured by ImmunoCAP® were all negative except for gelatin. Prick-prick skin testing revealed positive responses to Stona IB Gel®, gelatin KS and gelatin RP600, of which the latter two were included in the Stona IB Gel® capsule. From these test results, she was diagnosed with anaphylaxis due to gelatin, and to date she has had no further allergic symptoms since avoiding foods containing gelatin. In infancy she had received four vaccinations against diphtheria, pertussis and tetanus, which contained gelatin as a stabilizer. However, she had not developed allergic symptoms until this time. We hypothesize that she might be sensitized to gelatin by taking Stona IB Gel® during the preceding 4 days. This is the first case of anaphylaxis from the ingestion of an oral medication containing gelatin in Japan. Allergic reactions to gelatin are comparatively rare, but according to the past reports, the reactions were severe. Since many kinds of foods, cosmetics, pharmaceutical products, and medication contain gelatin, it is important to be aware of gelatin allergy.

Immunocompatibility of gelatin-based hydrogels to be applied as implant coatings for local regenerative treatment has been studied. First, the bio- and immuno-acceptability of the methacrylamide-modified gelatin hydrogels per se was screened. The results indicated that the hydrogels support cell growth. Metabolic activity of normal cells and permanent cell lines representing various cell types (endothelial, epithelial, fibroblast, and monocyte/macrophage) cultivated on the gelatin hydrogels was moderately lower compared to cells cultivated on tissue culture plastic. The cells cultivated on the hydrogels produced identical cytokines as the control cells although at lower levels. Importantly, no inflammatory activity, measured by nitric oxide and pro-inflammatory cytokine (IL-1α, IL-6, and TNFα) production, was observed in peritoneal cells and monocyte/macrophage RAW 264.7 cell line cultivated on the hydrogels. Finally, polyimide (PI) implantable membranes were surface-modified with gelatin hydrogels and screened for their in vivo immunocompatibility. Their histological examination performed after subcutaneous implantation in mice produced a sound proof of immunoacceptability. Normal tissue repair, mild cellular infiltration and edema mainly induced by the surgery were observed after 2 and 6 days. No adverse tissue responses were induced by the implants. Analysis performed after 4 and 9 weeks indicated areas of foreign body granuloma without formation of a fibrous capsule., (Copyright © 2013 Society of Plastics Engineers.)

Nanotechnologies are finding a growing range of applications in the food sector. Nanoparticles are used notably to add vitamins and other nutrients to foods and beverages without affecting taste and color. They are also used to develop new tastes, preserve food texture, control the release of flavors, improve the bioavailability of compounds such as antioxidants and vitamins, and monitor freshness with nanosensors. Crosslinked gelatin nanoparticles are a component of nano-sized carriers for nutrient and supplement delivery in foods and related products. This paper describes the production and characterization of polyclonal antibodies against gelatin nanoparticles. Two immunization schemes were investigated: subcutaneous injection with and without a first intravenous injection. Two enzyme-linked immunosorbent assay formats were used to characterize the antibodies: an inhibition format with an antigen-coated plate for detection of the immune response and a sandwich format for development of the method. The antibodies showed good sensitivity with an IC50 equal to 0.11 ng mL(-1) using indirect ELISA format and a good specificity for the nanomaterials, without significant cross-reactivity against native gelatin. The limit of detection was determined-0.42, 0.27, 0.26, and 0.24 μg mL(-1) for apple, orange juice, milk, and soft drink matrices, respectively. ELISA technology offers rapid, low-cost assays for screening foods, feeds, and beverages. We have studied a prototype ELISA for detection of gelatin-based nanocarrier systems. Fruit juices, milk, and a soft drink were the matrices selected for assay development.

Background: We have observed patients clinically allergic to red meat and meat-derived gelatin., Objective: We describe a prospective evaluation of the clinical significance of gelatin sensitization, the predictive value of a positive test result, and an examination of the relationship between allergic reactions to red meat and sensitization to gelatin and galactose-α-1,3-galactose (α-Gal)., Methods: Adult patients evaluated in the 1997-2011 period for suspected allergy/anaphylaxis to medication, insect venom, or food were skin tested with gelatin colloid. In vitro (ImmunoCAP) testing was undertaken where possible., Results: Positive gelatin test results were observed in 40 of 1335 subjects: 30 of 40 patients with red meat allergy (12 also clinically allergic to gelatin), 2 of 2 patients with gelatin colloid-induced anaphylaxis, 4 of 172 patients with idiopathic anaphylaxis (all responded to intravenous gelatin challenge of 0.02-0.4 g), and 4 of 368 patients with drug allergy. Test results were negative in all patients with venom allergy (n = 241), nonmeat food allergy (n = 222), and miscellaneous disorders (n = 290). ImmunoCAP results were positive to α-Gal in 20 of 24 patients with meat allergy and in 20 of 22 patients with positive gelatin skin test results. The results of gelatin skin testing and anti-α-Gal IgE measurements were strongly correlated (r = 0.46, P < .01). α-Gal was detected in bovine gelatin colloids at concentrations of approximately 0.44 to 0.52 μg/g gelatin by means of inhibition RIA., Conclusion: Most patients allergic to red meat were sensitized to gelatin, and a subset was clinically allergic to both. The detection of α-Gal in gelatin and correlation between the results of α-Gal and gelatin testing raise the possibility that α-Gal IgE might be the target of reactivity to gelatin. The pathogenic relationship between tick bites and sensitization to red meat, α-Gal, and gelatin (with or without clinical reactivity) remains uncertain., (Copyright © 2012 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.)

Purpose: Recombinant human gelatins with defined molecular weights were modified with cholesterol to make them amphiphilic in nature. We investigated the feasibility of these modified human gelatins acting as a carrier of antigenic proteins for inducing cellular immunity. The aim of this study was to synthesize novel and effective compounds for vaccine delivery in vivo., Methods: Two types of cholesterol-modified gelatin micelles, anionic cholesterol-modified gelatin (aCMG) and cationic-cholesterol modified gelatin (cCMG), were synthesized using different cholesterol derivatives such as the cholesterol-isocyanate (Ch-I) for aCMG and amino-modified cholesterol for cCMG. One was anionic and the other cationic, and therefore they differed in terms of their zeta potential. The aCMG and cCMG were characterized for their size, zeta potential, and in their ability to form micelles. Cytotoxicity was also evaluated. The modified human gelatins were then investigated as a carrier of antigenic proteins for inducing cellular immunity both in vitro in DC 2.4 cells, a murine dendritic cell line, as well as in vivo. The mechanism of entry of the polymeric micelles into the cells was also evaluated., Results: It was found that only cCMG successfully complexed with the model antigenic protein, fluorescein-isothiocyanate ovalbumin (OVA) and efficiently delivered and processed proteins in DC 2.4 cells. It was hypothesized that cCMG enter the cells predominantly by a caveolae-mediated pathway that required tyrosine kinase receptors on the cell surface. Animal testing using mice showed that the cationic cholesterol-modified gelatin complexed with OVA produced significantly high antibody titers against OVA: 2580-fold higher than in mice immunized with free OVA., Conclusion: Conclusively, cCMG has shown to be very effective in stimulating an immune response due to its high efficiency, stability, and negligible cytotoxicity.

Despite the use of collagen-derived scaffolds in regenerative medicine, little is known about the degradation mechanisms of these scaffolds in vivo. Non-crosslinked dermal sheep (NDSC) and gelatin disks were implanted subcutaneously in mice. NDSC disks showed a very low degradation rate, despite the presence of high numbers of macrophages and the influx of neutrophils. This was attributed to the presence of the matrix metalloproteinase inhibitor TIMP-1. The limited degradation occurred mainly in the later stages of the foreign body reaction, and could be attributed to (1) phagocytosis by macrophages due to a co-expression of Endo180 and MT1-MMP on these cells (intracellular degradation) and (2) the presence of MMP-13 due to an upregulation of the expression of the DDR-2 receptor (extracellular degradation). In contrast, gelatin disks degraded quickly, due to the efficient formation of large giant cells as well as the presence of MMP-13; the inhibitor TIMP-1 was absent. The DDR-2 receptor was not expressed in the gelatin disks. Endo180 and MT1-MMP were expressed, but at most times no co-expression was seen. We conclude that the physical state of collagen (native or denatured) had a dramatic outcome on the degradation rate and provoked a completely different foreign body reaction., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Embolization with microspheres is widely applied to treat uterine fibroids. However, the foreign body reaction that could result from the degradation of the microspheres remains to be evaluated to adequately appreciate the tissular tolerance to such biomaterials. We compared herein the in situ degradation of PMMA microspheres coated with polyphosphazene (PMMA-PPms) and trisacryl gelatin microspheres (TGms) and we thoroughly investigated the induced local inflammatory responses, at 1 and 4 weeks after uterine artery embolization in sheep, by using immunohistochemistry and microarray analyses. PMMA-PPms underwent an acute and partial degradation that was associated with the early recruitment of phagocytic cells (CD172a+ and MHCII+), and with the up-regulated expression of genes involved in the movement of phagocytes (ALOX5AP, CXCL2, CXCL5, IL8, PTGS2, YARS). By contrast, TGms were not degraded and triggered a different inflammation profile including the recruitment of FBR Giant Cells and T-lymphocytes (CD4+) and the increased expression of genes involved in lymphocyte activation (CXCL10, IL2RG, IRAK4, MALT1). Our results indicate that, in contrast to a non-degradable microsphere such as TGms which is associated to a poorly inflammatory foreign body reaction that rapidly resolves, PMMA-PPms, which is partially degradable, rapidly recruits and activates inflammatory phagocytes, thus delaying the resolution of the foreign body reaction., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Parvalbumins are well-known as major fish allergens. However, no quantitative analytical method is currently available for the determination of parvalbumins from different fish species. The aim of this study was the isolation of the various parvalbumins by the application of gel chromatography and dialysis and the development and validation of a competitive indirect ELISA for the determination of parvalbumins from various fish species. This ELISA method was applied to several fish gelatins and isinglass samples used in food production. The competitive ELISA was capable of detecting all tested parvalbumins within a range of 0.1-0.5 mg/L. No parvalbumin was detected in any of the investigated fish gelatins or in a fish skin used as raw material for fish gelatin production. Contrarily, isinglass was found to contain parvalbumin amounts of up to 414.7 +/- 30.6 mg/kg.

Aim: To study the induction of anti-tumor activity of murine peritoneal macrophages in vitro by porcine skin gelatin., Methods: Anti-tumor activity of the macrophages was evaluated with tritium thymidine uptake by target tumor cells. ELISA was used to measure amounts of cytokines secreted in culture medium., Results: The ability of the gelatin to induce anti-tumor activity of the macrophages was stronger than that of lipopolysaccharide of E. coli. Combination of the lipopolysaccharide and interferon-gamma synergistically stimulated the macrophages but that of the gelatin and interferon-gamma additionally did. The culture supernatant of the macrophages incubated with the gelatin also showed higher anti-tumor activity than that with the lipopolysaccharide though the lipopolysaccharide was more excellent than the gelatin in stimulating secretion of anti-tumor cytokines (IL-1, IL-6, TNF-alpha, IFN-gamma) by the macrophages. Anti-TNF-alpha antibody partially suppressed the anti-tumor activity of the culture supernatant of the macrophages incubated with the lipopolysaccharide but not with the gelatin. The gelatin induced anti-tumor activity of the macrophages of C3H/HeJ as well as C3H/HeN mice whereas the lipopolysaccharide did only in C3H/HeN mice. The macrophages stimulated in vitro by the gelatin exerted anti-tumor activity in vivo. Moreover, the gelatin stimulated peritoneal exudates cells in vivo when subcutaneously administered with them., Conclusions: Porcine skin gelatin induces anti-tumor activity of macrophages in mice and its magnitude is greater than that of lipopolysaccharide of E. coli. Its mechanism is different from that of the lipopolysaccharide but not fully clarified.

The aim of this study was to evaluate the influence of the coating of polymer implants upon the individual humoral immune response to the polymer matrix. Intramuscular implantation and explantation of samples from three different polyester vascular prostheses coated with collagen, gelatin, or human serum albumin was performed in LEW.1A rats and subsequently compared to sham operated control animals. Antibodies in serum samples were detected by means of enzyme immunoassays employing particles of pure polyester and the respective prosthesis, or solid phase bound coating substances as targets. In contrast to the controls, all animals with implants demonstrated a high antipolyester antibody response with a broad individual variability graduated according to the prosthesis coatings: gelatin > albumin > collagen. This was further significantly increased after the second implantation/first explantation and declined following the last explantation. Only animals with albumin-coated implants revealed specific antibodies to the coating as well as the strongest overall immunological reaction against the prosthesis already on day 8. Specificity of polymer antibodies was demonstrated by competitive inhibition of median antibody binding. Our results showed a specific immune reaction as a result of the applied polymer, which varied due to the surface-coating and individual factors.

The basic concept of tissue engineering, an actively applied technology in regenerative medicine, is the coordination between cells, scaffolds, and proliferation factors. Collagen and gelatin are materials that have mostly been used as scaffolds because of their excellent affinity for cells, they are biodegradable, and their ability to form gel. However, very few of the collagen or gelatin preparations used as tissue engineering material have been prepared with low levels of endotoxin, which may trigger fever, shock and a fall in blood pressure even in very minute quantities. Therefore we decided to decrease the content of endotoxin in gelatin so that this biomaterial is not harmful to the body but still maintains its properties, namely, bioaffinity and biodegradation for use in the fields of cell culture and regenerative medicine. In this paper, we describe a method whereby endotoxin could be removed from gelatin solution by using an ultrafiltration membrane with a molecular weight cut-off of 100 kDa and low endotoxin gelatin, endotoxin activity in 0.1% gelatin solution was below 0.03 EU/ml, was obtained as the resulting filtrate solution.

We describe a case of intraoperative gelatine-induced anaphylaxis whose diagnosis was delayed as the use of gelatine during surgical procedures was omitted for two times in patient's medical records. The subject is a 66-year old woman, with a negative medical history of atopy, food and drug allergy, with arterial hypertension on a course of beta-blockers and with bladder carcinoma requiring surgery. The patient had tolerated both general and local anaesthesia on several previous occasions. On the first occasion she experienced arterial fibrillation secondary to a severe episode of hypotension following local anaesthesia, while on a course of beta-blockers. On the second occasion she developed a very severe episode of hypotension followed by the outbreak of a generalised rash during general anaesthesia. The tryptase sera level was 109 mg/L one hour after the reaction had subsided, while the basal values were normal. On the third occasion the patient redeveloped severe hypotension and a generalised rash during general anaesthesia. The allergological work-up was negative, except for intradermal test with gelatine. A study of the intra-cellular cytokines in blood lymphocytes showed a production of IL4 from CD4+ lymphocytes after stimulation by gelatine. The patient underwent a successive surgical procedure without any adverse event.

Recently, an increasing number of adverse reactions in children inoculated with live attenuated virus vaccines containing gelatin have been reported. However, the distribution, magnitude and rate of gelatin sensitization in the Japanese population have not been established. Here, the purpose was to investigate the distribution of children with positive gelatin immunoglobulin G (IgG) and/or IgE in Japan and to ascertain whether the incidence of positive antigelatin antibody cases among the general population, as reflected in the sample employed here, has been increasing during the period in question. The presence of IgE and IgG antibodies were measured against gelatin in 1600 panel sera collected from different age groups of Japanese children in Hokkaido/Sapporo from 1979 through 1996. Among the subjects, 39 had gelatin IgG- and/or IgE-positive sera, and these were correlated with the time of obtaining the sera as well as with the age of the subjects. The older the subject and the later the period, the higher the sero-incidence. Japanese children have become increasingly sensitized to gelatin, especially since the mid-1990s.

Gelatin is obtained from bones and hides/skin, mainly from cows and pigs using alkaline or acidic processes. The use of bovine gelatin in feed, food, and pharmaceutical products has been restricted by regulatory authorities as a consequence of the outbreak of bovine spongiform encephalopathy (BSE). On the other hand, some religions ban the porcine gelatin for human consumption. Thus, there is a need for methods able to control the species origin of gelatins. The large similarity in structure of gelatins from different origins has made unsuccessful their differentiation by physicochemical methods. Moreover, the development of immunochemical methods has been hampered by the poor immunogenicity of gelatins. We obtained high titers antibodies upon immunization of rabbits with tyrosylated bovine and porcine gelatins. Using indirect and competitive indirect ELISAs we observed large differences in titers and specificity among rabbits and during the course of immunization. Some of the antisera were not sensitive to the species origin of raw material or to the process used for gelatin production and could be used for gelatin quantitation in food. Other antisera detected the porcine acidic gelatins with 10- to 30-fold higher sensitivity than their bovine counterparts and could be used for the differentiation of the species origin of gelatins. Lastly, other antisera were highly sensitive to subtle changes in conformation of gelatins obtained by alkaline or acidic processes such as a 1,000-fold higher reactivity of bovine acid hide gelatin compared to that of its limed counterpart or a 30,000-fold higher reactivity of porcine acid bone compared to that of its limed counterpart; such antisera could be used to monitor the process induced structural changes of collagen during its transformation to gelatin.

A gelatin/hyaluronic acid (GH) sponge has been fabricated by freeze-drying and cross-linking. The GH sponge was insoluble when cross-linked with 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide. The morphologies of sponges were investigated using a field emission scanning electron microscope. The porosity of the GH sponge increased with hyaluronic acid content. The GH sponge was biodegradable, as evidenced by implantation in Wistar rat subcutaneous connective tissue. Fibroblasts infiltrated into the sponge matrix, and regenerated collagen in the matrix to a level of 25% by 15 days after surgery. The GH73 sponge induced an acute inflammatory response compared with the GH91 sponge. This inflammatory response could have been stimulated by the presence of hyaluronic acid up to Day 10, as it decreased afterwards. The C-reactive protein of blood samples also indicated the same result. The blood tests and histological results show that GH sponges have good biocompatibility and low antigenicity for tissue engineering scaffolds.

From the early 1990s infants started to receive acellular pertussis vaccine combined with diphtheria and tetanus toxoids (DTaP) before live vaccines such as measles, rubella, and mumps vaccines, which contained gelatin as a stabilizer. Then, an increasing number of cases of anaphylactic/allergic reactions to those live vaccines were reported. Almost all these cases had a previous history of receiving three or four doses of DTaP containing gelatin.Anaphylactic/allergic reactions to live measles vaccine were analyzed using information obtained from the Reporting System, a retrospective study, as well as from the Monitoring System, a prospective study. Dramatic decreases in anaphylactic/allergic reactions to live measles vaccines were observed immediately after each manufacturer marketed gelatin-free or gelatin (hypo-allergic)-containing live measles vaccine, and since the end of 1998 reports on anaphylactic/allergic reactions to live measles vaccine have almost ceased.

Background: Although fish gelatin may represent a useful alternative to bovine or porcine gelatin, the clearly recognized high prevalence of fish allergy could increase the risk of anaphylaxis to gelatin. The rationale for investigating tuna gelatin rather than gelatin from more allergenic fishes is the availability of an industrial gelatin under development. The infrequent occurrence of tuna allergy should influence the safety of a derived product. The present study investigated IgE antibodies to tuna-skin-derived gelatin in adults and children with documented fish allergy or sensitization., Methods: Serum samples were taken from 100 consecutive patients with fish allergy or sensitization and tested for IgE antibodies against hydrolyzed or nonhydrolyzed gelatin extracted from tuna skin as compared to extracts from tuna flesh, tuna skin as well as bovine or porcine gelatin. Patients with tuna allergies or sensitization were sensitive to the same tuna species (yellowfin) as that from which the gelatin was obtained. IgE antibodies to these various extracts were analyzed using SDS-PAGE and immunoblotting., Results: Only 3 of the 100 serum samples tested gave evidence of reactivity to gelatin extracted from tuna skin. Cross-reactivity between bovine/porcine and fish gelatin was not observed., Conclusion: The risk of adverse reactions to tuna skin gelatin seems to be significantly lower than the risk of fish allergy. Fish gelatin may represent a valuable alternative to bovine or porcine gelatin., (Copyright 2003 S. Karger AG, Basel)

Objective: Anaphylaxis after immunization, although rare, is serious and potentially life-threatening. Understanding risk factors for this reaction is therefore important. Gelatin is added to many vaccines as a heat stabilizer. Japanese researchers have demonstrated a strong association between immediate hypersensitivity reactions to measles, mumps, rubella, varicella, and Japanese encephalitis immunizations and subsequent detection of anti-gelatin immunoglobulin E (IgE) antibodies. They suggested that previous receipt by these patients of diphtheria-tetanus-acellular pertussis vaccines with trace amounts of gelatin was responsible for the sensitization. We aimed to assess whether a similar association exists for vaccinees in the United States who reported anaphylaxis after receipt of measles-mumps-rubella (MMR) or measles vaccines and to review recent trends in reporting of hypersensitivity reactions., Methods: We conducted a retrospective case-control study. Cases of anaphylaxis that met a predefined case definition were identified from the US Vaccine Adverse Event Reporting System (VAERS). Mayo Clinic patients who received MMR vaccine uneventfully served as controls. The study subjects were interviewed to obtain the history of allergies. Sera from study subjects and their matched controls were tested for IgE antibodies to gelatin, whole egg, and vaccine viral antigens using solid-phase radioimmunoassay. Data from the Biologics Surveillance System on annual numbers of doses of MMR and varicella vaccines distributed in the United States were used to evaluate possible changes in reporting of selected allergic adverse events., Results: Fifty-seven study subjects were recruited into the study and interviewed. Of these, 22 provided serum samples for IgE testing. Twenty-seven subjects served as a comparison group and provided a sample for IgE testing; 21 of these completed an allergy history questionnaire. Self-reported history of food allergies was present more frequently in the interviewed study subjects than in the controls, whereas the proportions of people with other characteristics were similar in both groups. None of the interviewed people had a history of food allergy to gelatin. The level of anti-gelatin IgE antibodies was significantly higher among study subjects than among controls, whereas the levels of IgE antibodies against egg and all 3 viral antigens did not differ significantly. Of 22 study subjects, 6 (27%) tested positive for anti-gelatin IgE, whereas none of the 27 controls did. The rate of anaphylactic reactions reported to VAERS after measles virus-containing immunization in the United States between 1991 and 1997 is 1.8 per 1 million doses distributed. No substantial increase in the number of reported allergic events after frequently used gelatin containing MMR and varicella vaccines could be observed during the first 4 years (1997-2000) since the introduction of diphtheria-tetanus-acellular pertussis vaccines for use in infancy., Conclusion: Anaphylactic reactions to MMR in the United States are rare. The reporting rate has the same order of magnitude as estimates from other countries. Almost one fourth of patients with reported anaphylaxis after MMR seem to have hypersensitivity to gelatin in the vaccine. They may be at higher risk of developing anaphylaxis to subsequent doses of other gelatin-containing vaccines. These people should seek an allergy evaluation before such immunization.

Background: Anaphylaxis to measles, mumps, and rubella vaccines has been reported. It has been found that most of these reactions to live vaccines are caused by type I allergy with the bovine gelatin present in the vaccines as an allergen. Gelatin mainly includes denatured type I collagen, which consists of alpha1 and alpha2 chains. We previously reported that allergic reactions to gelatin are caused by the type I collagen alpha2 (alpha2[I]) chain., Objective: To aid in the development of gelatin that has little or no allergenicity in human subjects, we investigated epitopes of bovine alpha2(I) chain with use of IgE in gelatin-sensitive children., Methods: Serum samples were collected from 15 patients who had systemic allergic reactions to vaccines and high levels of specific IgE to bovine gelatin. Eleven overlapping recombinant proteins that cover bovine alpha2(I) were prepared with a bacterial expression vector. We examined IgE reactivity to these recombinant proteins by means of ELISA. Fifteen peptides covering a major reactive recombinant protein were synthesized. The IgE-reacting epitope was identified by means of IgE-ELISA inhibition with these synthetic peptides and pooled serum from the patients., Results: We found that of the 15 patients, 13 showed IgE reactivity to a recombinant protein (no. 3) spanning the central region of the collagenous domain ((418)Gly-(662)Pro). Furthermore, all 13 patients showed IgE reactivity to the 4-kd recombinant protein (no. 3a) spanning the region from (461)Pro to (500)Glu. In IgE-ELISA inhibition we found that a minimum IgE epitope of gelatin allergen was composed of the 10-amino-acid sequence (485)Ile-Pro-Gly-Glu-Phe-Gly-Leu-Pro-Gly-Pro(494). This sequence is not observed in the human type I collagen alpha1 and alpha2 chains, nor is it found in the bovine type I collagen alpha1 chain., Conclusions: We found that Ile-Pro-Gly-Glu-Phe-Gly-Leu-Pro-Gly-Pro is a major IgE epitope of the alpha2 chain of bovine type I collagen in patients with gelatin allergy. The degree of anaphylaxis to gelatin in vaccines might be reduced by digestion of this IgE-binding site in gelatin.

Background: Gelatin-specific cell-mediated immunity develops in subjects inoculated with gelatin containing DTaP vaccine. However, it is not yet known whether such established sensitization to gelatin disappears or persists with time., Objective: The aim of this study was to follow the patients with gelatin sensitization elicited by DTaP vaccination for their lymphocyte responsiveness and IgE, IgG antibody specific to gelatin over several years and to compare the activities with those at the time of enrollment into the study., Methods: We studied 28 subjects who developed positive lymphocyte proliferation test (LPT) after receiving gelatin containing DTaP vaccine and eight subjects who had a negative LPT after inoculation of non-gelatin DTaP. Determination of IgE, IgG antibodies and specific lymphoproliferative response directed against gelatin were performed at enrollment and on follow up., Results: None of the subjects had antibody to gelatin at enrollment and none developed gelatin IgE or IgG during follow-up. There was no significant difference in the SIs of the subjects receiving gelatin DTaP (P = 0.150, 95% CI, -0.198-0.032), whereas lymphocyte activity to gelatin increased between enrollment and follow-up in the subjects with non-gelatin DTaP (P = 0.011, 95% CI, 0.063-0.338)., Conclusion: Gelatin-specific lymphocyte activity persists at comparable levels for more than 3 years in subjects who acquire a positive LPT response to gelatin after receiving primary DTaP vaccine containing gelatin. Furthermore, five out of eight subjects initially with negative LPT to gelatin have been shown to acquire specific LPT with time.

Systemic immediate reactions including anaphylaxis to gelatin in vaccines have been reported. However, the number of such reports is very small compared with the number of children exposed to gelatin. The present study was designed to investigate whether susceptibility or resistance to gelatin allergy is associated with human leukocyte antigen (HLA) class II gene. Blood samples were obtained from 49 patients with gelatin allergy and specific IgE to gelatin. DNA-based HLA class II typing was performed to determine the DRB1, DQB1 and DPB1 alleles. Genotype frequencies were compared with those found in 240 unrelated controls. The frequency of DQB1*0303 (55.1%) was significantly higher in the patients than in the control subjects (32.1%). The frequency of DPB1*0402 was also significantly higher in the patients (32.7%) than in the control subjects (15.4%). On the other hand, the frequency of subjects carrying DRB1*15 (DRB1*1501 and DRB1*1502) was significantly lower among the patients group (18.4%) than among the controls (40.8%). We found that DQB1*0303 and DPB1*0402 were positively associated with the IgE response for gelatin, while DRB1*15 was negatively associated with it.

Background: Systemic allergic reactions to Japanese encephalitis (JE) vaccine that include urticaria, angioedema, and rash have been reported. In Japan, children who suffered from allergic immediate-type reactions to JE vaccine had antigelatin IgE in their sera. However, the immunologic mechanism of allergic nonimmediate-type reactions that consist of cutaneous signs appearing several hours or more after JE vaccination has not been defined., Methods: Serum samples were taken from 28 children who showed allergic nonimmediate-type cutaneous reactions to JE vaccine. Furthermore, serum samples were taken from 10 children who showed allergic immediate-type reactions with cutaneous signs and/or respiratory symptoms to JE vaccine. We have defined an immediate-type reaction as one occurring within 1 h after vaccination., Results: Of 10 children who showed immediate-type reactions, all had antigelatin IgE and IgG. Of 28 children who showed systemic nonimmediate-type reactions, one had antigelatin IgE and nine (32%) had antigelatin IgG. The child who had antigelatin IgE showed urticaria 2 h after JE vaccination., Conclusion: These results suggest that some children who showed allergic nonimmediate-type reactions to JE vaccine were sensitized to gelatin.

The frequency of HLA class I and II phenotypes was determined among 23 patients with positive gelatin IgE, eight of whom developed anaphylaxis, 18 patients who did not have gelatin IgE but who experienced non-immediate reactions after exposure to gelatin. HLA-DR9, which is unique to Orientals, was present in 56.5% of the gelatin IgE positive patients, as compared to control population frequency of 24% (P < 0.002). In the non-immediate reaction group, who did not generate IgE, phenotype distribution resembled controls. HLA-DR9 positive individuals have a relative risk of 4.1 for developing gelatin allergy with positive IgE.

We have previously found that most occurrences of anaphylaxis to live virus vaccines are caused by gelatin present in the vaccines as a stabilizer. After we published the evidence for the role of gelatin in anaphylaxis, vaccine manufacturers in Japan began to eliminate gelatin from live virus vaccines. In the present study, we tried to estimate its incidence before the gelatin elimination was started. Physicians and vaccine manufacturers submitted serum samples from children with anaphylaxis to measles, mumps, rubella or varicella vaccine to National Institute of Infectious Diseases (NIID) for 3 years from April 1994 to March 1997. Specific IgE to gelatin was assayed at NIID or two manufacturers by the CAP and ELISA methods. There were 44 children with life-threatening severe anaphylaxis (airway obstruction or anaphylactic shock) during the 3-year period, 41 of whom had anti-gelatin IgE. There were 64 children with mild anaphylaxis (without airway obstruction); 62 had anti-gelatin IgE. There were 100 children with only systemic cutaneous signs; 81 had anti-gelatin IgE. The estimates for the incidence of the severe anaphylaxis in 1994-1996 are: 6.84, 7.31, 4. 36, and 10.3 cases per million doses of gelatin-containing measles, rubella, mumps, and varicella vaccines, respectively.

Most of the children who showed systemic immediate-type reactions, including anaphylactic shock, to measles, mumps, rubella, and varicella vaccines had IgE antibodies to gelatin; thus we suspected that the allergic symptoms are caused by gelatin antigen, which is usually included in these live-virus vaccines as a stabilizer. We hypothesized that the anti-gelatin IgE is elicited by immunization with DTaP (diphtheria-tetanus-acellular pertussis) vaccines, which contained a small amount of gelatin as a spillover protein after purification of pertussis toxin. To test this hypothesis, we conducted a case-control study to determine whether children with anti-gelatin IgE had received gelatin-containing DTaP vaccines, and it was indeed found that all such children in the study had immunization histories that included the gelatin-containing DTaP vaccines. Based on these findings, the vaccine manufacturers had removed gelatin from all the DTaP and live-virus vaccines produced in Japan by 2000.

Background: This study was designed to evaluate the immunogenic characteristics of enzymatically digested gelatin, 'FreAlagin', employing the lymphoproliferative response in subjects with gelatin hypersensitivity. Our purpose was to assess the response of primed lymphocytes to the newly developed FreAlagin and compare it to the response to conventional gelatin., Methods: A gelatin-specific lymphocyte proliferation test (LPT) was performed in 110 children with adverse reactions to gelatin-containing vaccines, who showed positive gelatin-specific cell-mediated immunity and were thus diagnosed as having gelatin hypersensitivity. Gelatin-specific IgE was measured in all subjects. The antigenic activity of FreAlagin to lymphocytes was compared with that of conventional bovine gelatin. Positive and negative control specimens were obtained from the patients with anaphylaxis and from subjects inoculated with gelatin-free vaccine who showed no adverse reactions in order to establish the fluorometric ELISA system to determine IgE antibody to gelatin and LPT., Results: The lymphocyte activity against FreAlagin was much less than that to Wako gelatin and more than half of the subjects who reacted positively to Wako gelatin had a negative LPT to FreAlagin. Although 47% of the subjects had positive LPTs to FreAlagin, all but two still had lower SIs to FreAlagin compared with Wako gelatin., Conclusion: We conclude that the antigenic activity of FreAlagin as measured by the cell-mediated immune response is significantly less than that of conventional bovine gelatin. However, it is still necessary to perform clinical trials to show a reduced or absent clinical reactivity to FreAlagin in sensitized patients to conventional gelatin.

We recently found that most events of anaphylaxis to live attenuated viral vaccines containing gelatin as a stabilizer might be caused by the gelatin. However, the mechanism that the children were sensitized to gelatin was unclear. In Japan, both diphtheria-tetanus-acellular pertussis (DTaP) vaccines with and without gelatin are available. We explored the possibility that gelatin-containing DTaP vaccines before live viral vaccines sensitize children to gelatin. We received the serum samples of 87 children who had systemic immediate-type reactions including anaphylaxis to the vaccines from both physicians and vaccine manufacturers throughout Japan. We then surveyed the DTaP vaccination histories of the children who demonstrated anti-gelatin IgE. Of the above 87 children, 79 (91%) had anti-gelatin IgE. We successfully collected DTaP vaccination histories including the manufacturers' names and numbers of doses on 55 children. Only one child had not received any DTaP vaccine, the other 54 had received gelatin-containing DTaP vaccines and none received gelatin-free DTaP vaccines. We concluded that there was a strong causal relationship between gelatin-containing DTaP vaccination, anti-gelatin IgE production, and risk of anaphylaxis following subsequent immunization with live viral vaccines which contain a larger amount of gelatin.

Background: We recently found that four children who experienced systemic immediate-type reactions to varicella vaccine with gelatin had anti-gelatin IgE. We also found systemic non-immediate-type allergic reactions, which mainly consist of systemic cutaneous signs, appearing several hours or more after the vaccination., Objective: To investigate the relationship between immune responses to gelatin and non-immediate-type reactions to gelatin-containing varicella vaccines, we measured anti-gelatin IgE and IgG in the sera of the children with these allergic reactions., Methods: Serum samples were taken from 21 children who showed non-immediate-type reactions to varicella vaccines. As a positive control, serum samples were taken from 33 children who showed immediate-type reactions to varicella vaccine and had anti-gelatin IgE. As a negative control, serum samples were taken from 50 children who showed no reaction to the vaccine. We then examined anti-gelatin IgE and IgG in sera of the children., Results: Of 21 children with non-immediate-type reactions, two (10%) had anti-gelatin IgE and six (29%) had anti-gelatin IgG. In the positive control group, all 33 children with immediate-type reactions had anti-gelatin IgG as well as IgE. In the negative control group, all 50 children who showed no allergic reaction to varicella vaccines had neither anti-gelatin IgE nor IgG., Conclusions: These results suggest that the possibility exists that some non-immediate-type reactions to varicella vaccine are caused by immune reactions to gelatin.

Gelatin-specific T cell response was performed to determine whether a series of vaccinations with gelatin-containing DTP is a primary sensitization process in gelatin allergy. Thirty-seven recipients with gelatin-containing DTP who developed adverse reactions after vaccination and eight recipients of DTP without gelatin who also developed adverse reactions were studied. In addition, 10 subjects receiving gelatin-containing vaccine and 10 subjects inoculated with non-gelatin vaccine who did not show any adverse reactions were also investigated. All subjects inoculated with gelatin-containing DTP vaccine showed positive T cell responses against gelatin, however, occurrence of adverse reactions did not correlate with T cell responses. We conclude that DTP vaccine containing gelatin induces sensitization to gelatin in the recipients, but the mechanism of local reactions remains unknown.

Background: Anaphylactic reactions to measles, mumps, and rubella vaccines, including gelatin as a stabilizer, have been reported. It had been found that most of these reactions to live vaccines are caused by the bovine gelatin included in these vaccines. Gelatin mainly includes denatured type I collagen, which consists of alpha1 and alpha2 chains., Objective: The current study was designed to investigate the IgE reactivity to alpha1 and alpha2 chains of bovine type I collagen in gelatin-sensitive children., Methods: Serum samples were taken from 10 children who had anaphylaxis to the vaccines and high levels of specific IgE to bovine gelatin. Bovine type I collagen was isolated from bovine skin and then separated to alpha1 and alpha2 chains by column chromatography. IgE reactivity to denatured type I collagen and its alpha1 and alpha2 chains was analyzed by immunoblotting, ELISA, and histamine release from the mast cells passive sensitized with IgE antibodies in pooled serum of the children., Results: All children had specific IgE to bovine type I collagen. Furthermore, IgE antibodies in their sera reacted with the alpha;2 chain but not with the alpha1 chain. Similarly, the mast cells sensitized with pooled sera in the children showed alpha2 chain-specific histamine release but not alpha1 chain-specific histamine release., Conclusion: In gelatin allergy denatured bovine type I collagen is a major allergen and IgE-binding sites exist in the alpha2 chain of type I collagen.

We examined anti-gelatin IgG in sera of children who suffered from systemic adverse reactions upon immunization with gelatin-containing live virus vaccines. In the group of 30 children who had immediate-type reactions and anti-gelatin IgE, 30 (100%) had anti-gelatin IgG and 29 (96%) had anti-gelatin IgG4. In another group of 75 children who had nonimmediate-type reactions and no anti-gelatin IgE, 22 (29%) had anti-gelatin IgG and six (8%) had IgG4. The IgG positivity well correlated with the lymphocyte proliferation assay positivity. In contrast, as a negative control, all 24 children who had no allergic reaction to live virus vaccines had no anti-gelatin IgG and IgG4. The results suggest that immune-response to gelatin may play a role in the pathogenesis of systemic nonimmediate-type reactions to the live virus vaccines.

Background: The immune mechanism of gelatin allergy, especially the participation of TH1 and TH2 cells and their cytokine secretion, has not been investigated., Objective: We investigated the characteristics of T lymphocytes from patients allergic to gelatin-containing vaccine by secondary in vitro stimulation of circulating mononuclear cells with gelatin., Methods: We studied 8 children with a history of immediate-type reactions and 8 with nonimmediate-type reactions after inoculation of gelatin-containing vaccine. The expression of IFN-gamma (TH1 ), IL-2 (TH1 ), IL-4 (TH2 ), and IL-13 (TH2 ) mRNA was examined semiquantitatively by using a reverse transcriptase PCR. IgE antibody to bovine gelatin was measured with the fluorometric ELISA system, and gelatin-specific T-cell responses were detected by an in vitro lymphocyte proliferation assay., Results: Patients with an immediate reaction all had gelatin-specific IgE antibody, whereas others did not. However, all patients exhibited positive T-lymphocyte responses specific to gelatin. Lymphocytes from subjects with nonimmediate-type reactions generally expressed very weak or sometimes no IFN-gamma, IL-2, or IL-13 genes and especially no IL-4 gene. On the other hand, the lymphocytes of subjects with immediate-type reactions significantly expressed not only IL-4 and IL-13 but also IFN-gamma and IL-2 mRNA., Conclusion: Our observations suggest that both gelatin-specific TH2 and TH1 responses are involved in the pathogenesis of the immediate reaction to gelatin. The gelatin-specific IL-4 and/or IL-13 responses consistently observed in patients with an immediate reaction may be associated with the production of gelatin-specific IgE antibody.

It has been reported that most children who showed anaphylaxis to measles, mumps and rubella vaccines containing bovine gelatin as a stabilizer have anti-bovine gelatin IgE. The present study was designed to investigate the reactivity of IgE in bovine gelatin-sensitive children to gelatins from various animals, and the antigenic cross-reactivity between the gelatins. Serum samples taken from 10 children who showed anaphylaxis to vaccines containing bovine gelatin were used in this study. The level of anti-bovine gelatin IgE in these serum samples ranged from 11.0 to 251 Ua/ml. The IgE in most of the children reacted to kangaroo and mouse gelatins, to which they had had little or no exposure as a food or a vaccine stabilizer. The IgE binding to kangaroo and mouse gelatins was completely inhibited by bovine gelatin, whereas reciprocal inhibition was not complete, indicating that antigenic cross-reactivity is present between the mammalian gelatins. Only one child had strong IgE reactivity to fish gelatins, and this reactivity was not inhibited by bovine gelatin, indicating that no antigenic cross-reactivity exists between bovine and fish gelatins. Most of the children who displayed sensitivity to bovine gelatin showed IgE reactivity to other mammalian gelatins. This reactivity may be due primarily to the antigenic cross-reactivity between mammalian gelatins.

An uncommon reaction to varicella vaccine has been urticaria. Based on two reports of urticaria believed to be due to gelatin in recipients of measles-mumps-rubella vaccine, we suspected gelatin as the cause of generalized urticaria in two children after varicella vaccination. Intradermal testing with gelatin yielded a wheal and flare reaction in both children. We conclude that children known to be allergic to gelatin should not receive Oka/Merck varicella vaccine (VARIVAX).