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Background: Several studies demonstrated the efficacy of intralesional purified protein derivative (PPD) immunotherapy in warts eradication. Nevertheless, the precise induced immune mechanisms are undetermined. Injected PPD is hypothesized to induce a delayed hypersensitivity reaction associated with cytokines release. Interleukin (IL)-18 has a major role in defense against viral infection via inducing interferon-γ release from T-helper 1 and natural killer (NK) cells. Moreover, IL-18 triggers Fas ligand expression on cytotoxic T cells and NK cells enhancing their cytotoxicity against virally infected cells., Aim: The aim of this study was to assess the role of IL-18 in the response to intralesional PPD injection in patients with warts., Methods: The study included 25 patients with warts and 25 HCs. Patients underwent PPD skin test, and only patients with positive tests were included and received intralesional PPD injections starting 72 h after the test then every 2 weeks until wart clearance or a maximum of 3 sessions. Serum IL-18 level was measured via enzyme-linked immune-sorbent assay in patients (pre-treatment and 2 weeks after the last injection) and HCs., Results: After 3 sessions of injection, six (24%) patients were designated responders, nine (36%) patients showed partial response, and 10 (40%) patients were designated non-responders. Serum IL-18 level, post-treatment, was significantly higher than pre-treatment level (p = 0.025) and level in HCs (p = 0.036). Furthermore, the post-treatment level was significantly higher in responders than non-responders (p = 0.025)., Conclusion: IL-18 is probably implicated in the immune mechanisms induced by PPD injection that cause eradication of warts., (© 2022 Wiley Periodicals LLC.)

Background: The immune system plays an important part in the clearance of molluscum contagiosum (MC) and, therefore, there has lately been a trend in using immunotherapy in MC therapy. Tuberculin-purified protein derivatives (PPDs) and topical cantharidin have not earlier been compared with their effectiveness in therapy Aim: The aim of this research was to determine the effectiveness and security of intralesional immunotherapy in the therapy of MC with tuberculin PPD versus topical cantharidin Patients and methods: Twenty patients with various MC lesions received topical cantharidin as control (group A) and 20 MC patients received intralesional tuberculin PPD following prior intradermal immunity tests (group B‏). Results: Complete clearance of lesions was detected in 90.0% of patients in the cantharidin group; the partial response was detected in10.0% of the patients. However, in the PPD group, 85% of the patients showed a complete response and 15% showed a partial response, with no significant difference in the clinical response between the two groups. Mild side effects were detected‏. Conclusion: The results suggest that intralesional PPD and topical cantharidin 0.7% are effective and safe treatment modalities, but benefits of intralesional PPD is being a simple, effective and safe treatment with tolerable pain and can be an alternative treatment for multiple resistant types‏.

Background: Despite the numerous studies on the use of purified protein derivative (PPD), a protein extracted from Mycobacterium tuberculosis, in verruca vulgaris, there is no standardized regimen, and efficacy of single versus multiple injections has not been compared., Methods: This is a randomized, open-label, superiority trial. Sixty-six patients with at least three warts in two different anatomic sites were randomized into two groups: a single injection (n = 29) and multiple injection (n = 29) groups. Patients were treated every 2 weeks until a maximum of six sessions., Results: Multiple injections (79.3%) showed superior clearance rates compared to a single injection of PPD (58.6%) (P-value = 0.0236). Multiple injections also exhibited faster clearance at each time point (P = 0.048). Pain was statistically more significant in the multiple injection group (P = 0.0005). There was no statistically significant difference in incidence of adverse events (P = 0.1795). Amongst all cleared patients in both groups, there were no recurrences after 6 months., Conclusion: Multiple injections of warts with PPD cleared more patients with multiple common warts than the use of single injections at the end of 12 weeks and were faster in clearing patients at every time point. Single injection was better tolerated than multiple injections. Both treatments exhibited similar safety profiles and recurrence rates., (© 2019 The International Society of Dermatology.)

Background: Present day therapeutic modalities for viral warts are mostly ablative in nature, limited by high recurrence rates and are unsuitable for numerous lesions. Immunotherapy has the potential to overcome these limitations., Aims: This study aimed at comparing efficacy and safety of and quality of life changes with intradermal purified protein derivative (PPD) of tuberculin antigen and Mycobacterium w (Mw) vaccine in immunotherapy of warts., Methods: Patients with multiple (≥5) warts were randomized (1:1) into two groups (PPDand, Mw vaccine groups). Fortnightly, 0.1 ml of either medicine was injected intradermally over the deltoidregion till complete resolution or a maximum of six doses. Patients were followed-up for another 3 months for recurrence., Results: Sixty-four participants received either PPD or Mw vaccine. The number of warts were comparable at baseline (P = 0.089, Mann-Whitney test), and reduced significantly with treatment in both groups (P < 0.001, Friedman's ANOVA), as seen from the fourth follow-up onwards with Mw and fifth follow-up onwards with PPD (P < 0.05, Post hoc Dunn's test). Intergroup comparison showed significantly more (P < 0.05, Mann-Whitney test) reduction with Mw than PPD at the sixth and seventh follow-up. The size of warts also reduced significantly (P < 0.001) in both groups from the third follow-up onwards. Complete remission was more (P = 0.539, Fischer's exact test) in the Mw group (68.8%) than the PPD group (50%); and was significantly higher (P = 0.049, Mann-Whitney test) in patients having shorter duration of warts. Adverse events were significantly more (P < 0.001) with Mw including ulceration (50%), discharge (15.6%), pain-swelling-induration and scar at the injection site (97% each), whereas some of those receiving PPD noted erythema and scaling at the injection site (18.8%), and post-inflammatory hyperpigmentation (12.5%). No recurrence was seen till the end of the study., Limitation: Unicentric trial., Conclusion: Intradermal injection of Mw vaccine was more effective but had a higher incidence of adverse effects compared to PPD of tuberculin antigen in patients with warts., Competing Interests: None

The skin tuberculin test (TST), an example of a delayed-type hypersensitivity (DTH) reaction, is based on measuring the extent of skin induration to mycobacterial tuberculin (PPD). Little is known about the genetic basis of TST reactivity, widely used for diagnosing TB infection. The study investigated the relationship of the single base change polymorphic variants in CD14 gene (CD14(-159C/T)) with the development of DTH to PPD in BCG-vaccinated Polish Caucasian individuals. We found persistent lack of TST reactivity in about 40% of healthy subjects despite receiving more than one dose of BCG. The TST size was negatively correlated with the number of BCG inoculations. The distribution of C/T genotype was significantly more frequent among TST-negative compared with TST-positive individuals. The concentration of serum sCD14 was positively associated with mCD14 expression, but not with the TST status or CD14(-159C/T) polymorphism. A significant increase in mCD14 expression and serum sCD14 levels was found in TB group. We hypothesize that CD14(-159C/T) polymorphic variants might be one of genetic components in the response to attenuated M. bovis BCG bacilli.

Tuberculin skin testing was performed on a 5-year-old girl in Phnom Penh, Cambodia. She had been immunized by Bacille de Calmette et Guérin. She was tested because of a palpable cervical node and a slightly elevated temperature. Within 48 h, a deep necrotic lesion appeared on the volar aspect of the left arm. The lesion was treated locally, and the child was not treated for suspected TB. To our knowledge, this is the first instance of necrosis in 11,392 people who received Tubersol doses since 1996 to date at our International Vaccination Center, for an estimated incidence of 0.18 per 1,000 (95% Poisson 0.04-0.70 per 1,000 doses used). At a follow-up consultation after 77 days, the lesion had scarred and the child showed no signs suggestive of active TB. Although latent TB infection remains the most likely diagnosis, other types of mycobacterial infection may be considered in the tropical setting and in the absence of signs suggestive of active TB.

This brief communication describes the successful treatment of acute systemic anaphylaxis in a wild-born but captive infant western lowland gorilla (Gorilla gorilla gorilla) in the Republic of Congo. The infant demonstrated signs of acute respiratory distress, lingual swelling, and reaction to intradermal tuberculin, given 55 hr earlier. Details of the treatment with steroids, anesthetic induction, and i.v. epinephrine are all reported, and potential antigens that may have initiated the anaphylactic shock are discussed.

Factors predisposing to individual susceptibility to contact allergic dermatitis are ill defined. This study was designed to characterize the response of allergic and tolerant individuals' T-lymphocytes after exposure to p-phenylenediamine (PPD). Peripheral blood mononuclear cells (PBMCs) from allergic patients proliferated when treated with PPD and Bandrowski's base (BB) and secreted IL-1alpha, -1beta, -4, -5, -6, -8, -10, and -13; IFN-gamma; tumor necrosis factor-alpha; MIP-1alpha/beta; MCP-1 (monocyte chemotactic protein-1); and RANTES. PBMCs from tolerant individuals were stimulated to proliferate only with BB, and they secreted significantly lower levels of Th2 cytokines. Principal component analysis showed that genes are differentially expressed between the patient groups. A network-based analysis of microarray data showed upregulation of T helper type 2 (Th2) gene pathways, including IL-9, in allergic patients, but a regulatory gene profile in tolerant individuals. Real-time PCR confirmed the observed increase in Th2 cytokine gene transcription in allergic patients. Purified CD4+ and CD8+ T cells from allergic patients were stimulated to proliferate and secrete Th2 cytokines following antigen exposure. Only CD4+ T cells from tolerant individuals were stimulated by BB, and levels of Th2 cytokines were 80% lower. The nature of the antigenic determinant stimulating PBMCs and levels of Th2 cytokines, including IL-9, was confirmed in a validation cohort. These studies show increased activity of Th2 cytokines in CD4+ and CD8+ T cells from individuals with allergic contact dermatitis.

Background: Errors involving the mix-up of tuberculin purified protein derivative (PPD) and vaccines leading to adverse reactions and unnecessary medical management have been reported previously., Objectives: To determine the frequency of PPD-vaccine mix-ups reported to the US Vaccine Adverse Event Reporting System (VAERS) and the Adverse Event Reporting System (AERS), characterize adverse events and clusters involving mix-ups and describe reported contributory factors., Methods: We reviewed AERS reports from 1969 to 2005 and VAERS reports from 1990 to 2005. We defined a mix-up error event as an incident in which a single patient or a cluster of patients inadvertently received vaccine instead of a PPD product or received a PPD product instead of vaccine. We defined a cluster as inadvertent administration of PPD or vaccine products to more than one patient in the same facility within 1 month., Results: Of 115 mix-up events identified, 101 involved inadvertent administration of vaccines instead of PPD. Product confusion involved PPD and multiple vaccines. The annual number of reported mix-ups increased from an average of one event per year in the early 1990s to an average of ten events per year in the early part of this decade. More than 240 adults and children were affected and the majority reported local injection site reactions. Four individuals were hospitalized (all recovered) after receiving the wrong products. Several patients were inappropriately started on tuberculosis prophylaxis as a result of a vaccine local reaction being interpreted as a positive tuberculin skin test. Reported potential contributory factors involved both system factors (e.g. similar packaging) and human errors (e.g. failure to read label before product administration)., Conclusions: To prevent PPD-vaccine mix-ups, proper storage, handling and administration of vaccine and PPD products is necessary.

Temporary henna tattoo, which has become popular among young people, is obtained from the mixture of the plants Lawsonia alba or Lawsonia inermis and paraphenylenediamine (PPD). In forming reactions frequent development of anti-PPD substance is noticed. A 13-year old boy who started itching, erythema, enduration on the application area, increasingly urticarial rash, conjunctivitis and swelling of the lips 48 h after being applied the temporary henna tattoo was hospitalized. He had a local reaction to henna tattoo when he was 5-year old. He was treated with parenteral corticosteroids and oral antihistaminic drugs. Skin reactions persisted for 18 days. The patient showed no early reaction to henna 10% and PPD 1% concentration in saline solution but did late reaction (after 48 h) to PPD in diameter of 12x13 mm in prick test in 3 weeks after the reaction. A case who developed angioneurotic edema and urticaria to temporary henna tattoo noticed that the henna tattoo is not an innocent application and young people need to be informed on this subject.

The rates of positive tuberculin skin test (TST) reactions and BCG scarring after BCG vaccination vary between studies and populations. Tuberculin reactivity and BCG scarring may be related to better child survival in low-income countries. We therefore studied determinants for TST reaction and scarring in Guinea-Bissau. In a cohort of children born in suburban Bissau from March 2000 to July 2002, we assessed a Mantoux test with Purified protein derivative (PPD) (SSI, 2 T.U.) at 2 (2689 children), 6 (N=2148) and 12 months (N=1638) of age, and BCG scar was assessed at 2 (N=2698) and 6 months (N=2225) of age. In a subgroup of the children the vaccination technique was monitored by direct observation of post-vaccination wheal and route of administration. Three different types of BCG vaccine supplied by the local Extended Programme on Immunization were used. At 6 months of age the rate of PPD reactors (>1mm) after BCG vaccination was 25% and the rate of scarring was 89%. One BCG strain was associated with fewer PPD reactors (OR=0.54 (0.31-0.91)) and BCG scars (OR=0.13 (0.05-0.37)) and larger post-vaccination wheals produced more PPD reactions (OR 1.21 (95% CI 1.02-1.43)) and BCG scars (OR 1.66 (1.24-2.21)). In the multivariable analyses of BCG-vaccinated children assessed at 6 months of age, monitoring of vaccination technique and type of BCG vaccine were important. This was not changed by control for other determinants, including sex, season, vaccination place, birthplace, ethnic group, low birth weight, place of residence, education and civil status of mother. We reason that vaccination technique and BCG strain are important for PPD reaction and scarring in response to BCG vaccination. Considering that these responses are associated with better infant survival, the importance of monitoring vaccination technique and of different BCG strains should be evaluated with respect to infant mortality.

Earlier studies reported the associations among testosterone hormone, autoimmunity, and left-handedness. In the present study, sex differences in tuberculin reaction, a measure of cell-mediated hypersensitivity, serum free and total testosterone levels in controls and patients with autoimmune diseases were studied. There was a sex difference in right and left tuberculin reactions in controls, but not in patients. Both right and left tuberculin reactions were smaller in male and female patients than male and female controls. Free and total testosterone levels were higher in male controls than in male patients. Total testosterone levels were higher in female controls than in female patients. These results suggest that autoimmune diseases may be associated with a decrease in the blood testosterone concentrations.

A tuberculin survey was conducted among 45988 children with BCG scar and 54227 children without BCG scar between 1-9 years of age and residing in selected rural areas of three defined zones of India. About 45-60% of the BCG-vaccinated children elicited reactions < 5 mm in size and about 70-80% had reactions < 10 mm. Therefore, in the majority of children (showing tuberculin reaction of < 10 mm), BCG-induced tuberculin sensitivity does not interfere with interpretation of tuberculin test. The study also revealed that a proportion of reactions among BCG vaccinated children in 5-9 mm, 10-14 mm and 15-19 mm range may be attributable to BCG vaccination. Therefore, reactions between 10-14 mm and especially 15-19 mm among the vaccinated children must be interpreted carefully. However, 19 mm was observed as the upper limit for BCG induced tuberculin sensitivity and all reactions >- 20 mm in size may be considered to be due to infection with tubercle bacilli, irrespective of the BCG vaccination status.

In the Kharkov Region, the rate of tuberculosis infection in children was 28.8%; among them children with a curve of tuberculin reactions was 3.8%; most of them had a moderate sensitivity to tuberculin. The remaining 71.2% of the examinees were not infected with tuberculosis; more than 50% of them (41.1%) had postvaccinal allergy.

The recent rise in the incidence of allergic diseases, including allergic dermatoses, requires a comprehensive approach to solving a number of problems associated with this disease. Analyzing the case reports of 62 children with allergic dermatoses has indicated that this is a particular contingent of children, which needs a more careful approach to different preventive measures, to interpreting tuberculin reactions and hence to substantiating the use chemotherapeutical prevention. A graded skin tuberculin test and an immunological study should be performed in critical cases.

There was a consecutive reduction in the incidence of residual changes in the lung and tuberculin hypersensitivity, which coincides with the periods of using different BCG vaccination methods in adults at risk for tuberculosis. In persons who were born in 1961-1962 or later when intracutaneous administration was used, these figures were 3.4 and 3.9 times lower than in those born before 1961-1962. The incidence of residual changes, tuberculin sensitivity in adult examinees were greater than the similar parameters in the general population. To detect and to follow up persons of these groups are pressing for stabilization of the epidemiology of tuberculosis.

A group of 64 children with monotonous tuberculin sensitivity was analyzed. Intrathoracic lymph nodal tuberculosis (ITLNT) was revealed in 26 (41%) children. The remaining 38 (59% children with tuberculosis infection received a course of preventive treatment by taking into account the presence of risk factors. After tuberculosis treatment in children with ITLNT and tuberculous infection, papules due to Mantoux test significantly reduced in size.

Experiments on 56 rabbits infected with microorganisms of the genera Mycobacterium, Nocardia and Rhodococcus revealed that in response to the action of different antigens used T and B systems of immunity induced synthesis of antibodies reactive with nonspecific antigens (mycobacterial antigens, tuberculin). In some cases the statistically significant correlation between the dynamics of blast transformation and the specific lysis of lymphocytes in animals with Nocardia and Rhodococcus infections (in comparison with the controls) was determined when P.P.D. tuberculin was used as specific antigen. In the rabbits sera infected by Nocardia and Rhodococcus complement-fixation and hemagglutination antibodies to mycobacterial antigens were detected. These rabbits also exhibited skin reaction to P.P.D. tuberculin. The presence of common group-specific antigens in Nocardia and Rhodococcus, as well as in mycobacteria, determined the capacity of the former to sensitize experimental animals to tuberculin, with should be taken into consideration in making the allergic test to tuberculosis.

In screening patch testing of hairdressers with occupational contact dermatitis, multiple positive reactions to hair dye-related chemicals, such as p-phenylenediamine (PPD), p-toluenediamine x 2HCl (PTD) and p-aminophenol (PAP), a fabric dye p-aminoazobenzene (PAB), and a tar dye Sudan III, were frequently encountered. To investigate individual skin sensitization potency and the cross-reactivities among above chemicals, a guinea pig maximization test with the above 5 chemicals was performed. In each group, 6 animals were induced with one of the chemicals at 0.1% concentration by intradermal injection and at 1.0% by topical application. The animals were challenged with all 5 chemicals in concentrations of dilution by 10 from 0.1% to 0.001%. Under the conditions of 0.1% challenges, similar sensitization potencies were observed in PPD (6/6), PTD (6/6), PAP (5/6) and PAB (6/6) groups, but no positive reactions were elicited in the Sudan III group. The cross-reactivities to PPD were confirmed in the animals challenged with PTD (6/6), PAP (6/6), PAB (6/6) and Sudan III (3/6). In the PTD-induced group, positive responses to cross-challenges were elicited by PPD (5/6), PAP (3/6), PAB (5/6) and Sudan III (1/6). The cross-reactivities to PAP were observed only with PPD (2/5) and PAB (5/5). PAB-induced animals responded only to PPD (1/6). The results indicate that all these chemicals except Sudan III are strong sensitizers. Their cross-reactivities are different in sensitized conditions, respectively. The cross-reactivities to PPD were higher than those to PTD, PAP and PAB.

The Karviná district (northwestern part of North Moravia and Silesia) is typical by its industrial character, above all mining of black coal which is coked and which led to the devastation of the countryside. The ratio of light industry is low. In a small area (347 km2) there is a population of 824 inhabitants per km2. The population is concentrated in particular in urban agglomerations of the flat block type. Up to 1990 almost 55% of the population was employed in heavy industry. Due to its industrial activities, incl. metallurgical plants and ironworks in nearby Ostrava and Trinec, the district is one of the areas with a heavily contaminated atmosphere in particular with solid aerosol containing toxic metals (the values of solid aerosol varied on average between 100 and 150 micrograms/ml), the elevated values of Nox due to contamination from traffic and polyaromatic hydrocarbons were not negligible either during the investigation period. Since 1968 an endemic incidence of mycobacteria has been recorded which is due to Mycobacterium kansasii. At first only an occasional incidence was involved, since 1973 there has been a more substantial increase with a maximum in 1983 (64 cases) and thus up to 1995 there are 961 cases on records, incl. 787 (81.8%) in men and 174 (18.2%) in women. From the total number of recorded M. kansasii in 937 instances (97.3%) the lungs were affected (777 men, 160 women). The mean annual incidence was 34.3 cases, i.e. 12.03 per 100,000 population (28.1, i.e. 20/100,000 in men, 6.2, i.e. 4.28/100,000 in women). As to age, 78.8% of cases are recorded in the age bracket from 25 to 64 years (in men 81%, in women 68.9%). The highest specific morbidity in men is in the age group from 45-54 years (on average 73.13 per 100,000 per year), in women in the age group from 75 to 84 years (on average 9.75 per 100,000 per year). As to occupation, the ratio of mine employees at the time of contraction of the disease (incl. retired miners) was 52.2%), other workers 14.6%--all stigmatized by an increased dust concentration in other workplaces in heavy industry. As far as the domicile is concerned, the incidence was by far highest in Havírov (more than 56%), followed by Karviná (26.7%). These towns are inhabited mostly by miners. As to the mode of assessment 68.8% cases were diagnosed on account of pulmonary complaints and during dispensarization (stigmatization by dust) and 24.6% cases during preventive radiodiagnostic examinations of miners lungs. It did not prove possible to reveal the source. Interhuman transmission was not proved in any of the patients. The causal agent of the infection is most probably transmitted through water (by the aerogenic route). M. kansasii was isolated from drinking water (560 samples, in 7% M. kansasii was found), as well as in industrial water. In 1971-1995 a total of 1231 samples of industrial water were examined (scrapings and untreated water). From these M. kansasii was isolated in 43.7% (538 specimens). In soil samples (93) and small mouse-like rodents (187) M. kansasii was not detected. The authors confirm that the development of disease depends in a decisive way on the susceptibility of the individual which in turn depends in particular on exposure to dust with possible lung damage and contamination of the atmosphere. In the district there is a high incidence of recurring acute diseases of the airways in children, incl. allergies affecting the airways. In the towns of Karviná, Havírov, Orlová, Bohumín and Ceský Tĕsín there is a high ratio of children with reduced immunity. In November 1981 to January 1982 987 first form pupils were examined for postvaccination TB allergy (standard tuberculin and avian tuberculin were used). The reactivity to avian tuberculin was higher than to standard tuberculin (see results). The highest ratio of intense reactions (30%) was recorded in children from Havírov where there is also the highest specific (and simple) incidence in adults.

Eight hundred and sixty-six one-month-old female calves were vaccinated using heat-killed Mycobacterium paratuberculosis in oil during a five-year period. Seven hundred and twenty-one bull calves and 379 female calves served as nonvaccinated controls. Two large herds were used in the study. The calves were tested by faecal culture and by serologic tests on the day of vaccination, at 3, 6, 9 and 12 months of age, at breeding and on the day of parturition. The results were evaluated by trend analyses. Following vaccination, the faecal shedding of bacteria was greatly reduced as determined by annual faecal microscopic tests. During the last 6 months of the experiment as few as 9 samples from 612 cattle proved positive by microscopy and/or culture. The number of seropositive animals and the antibody titres (CFT and AGID) increased during the first three years, then declined.

The present study analyzes some clinical and immunological aspects of the giant reaction (GR) in lepromatous leprosy. Sixteen out of a total of 147 (10.9%) lepromatous patients developed the clinical features of GR upon the intradermal administration of PPD; most (14 of 16) GRs occurred in bacteriologically positive cases. GR precipitated an episode of erythema nodosum leprosum (ENL) in three patients. In addition, patients with GR showed enhanced in vitro response to PPD, by the lymphoproliferation test and interferon-gamma assay, as compared to either PPD-negative individuals or PPD-positive patients without GR. Therefore, cell-mediated-immune response to mycobacterial antigens is present in lepromatous patients with GR. It is suggested that the exacerbated in vivo response to PPD in lepromatous leprosy is the result of an increased immunoreactivity to the antigen, which well may be associated with the local and/or systemic release of cytokines [tumor necrosis factor-alpha (TNF alpha) and interferon-gamma (IFN gamma)] by the inflammatory cells. These episodes may, in fact, play an important role in determining the development of disabilities and reactional states, thereby interfering with the prognosis of leprosy disease.

It is demonstrated that tuberculin electrophoresis in chemoprophylaxix for M.tuberculosis infection in adolescents with a marked of hyperergic reaction to the Mantoux test (2TU) contributes to enhancement of nonspecific immunological reactivity, to a decline in immunospecific reactions, and reduction in the response to the Mantoux test (2TU).

After Mantoux testing with purified protein derivative (PPD) equivalent to 5 tuberculin units (TU), a 28 yr old man developed extensive erythema, induration and proximal lymphangitis. This is the only such case observed after Mantoux testing in approximately 500,000 subjects during 10 yrs in the Greek Army.

For the demonstration of a cell-mediated sensitisation, tuberculin allergics, chromate allergics, penicillin allergics, and controls were investigated. The method used was the measurement of leukocyte migration inhibition in a Teflon skin chamber with and without addition of antigen, which approaches to testing under in vivo conditions. In 10 of 11 tuberculin allergics, 6 of 7 chromate allergics, and 7 penicillin allergics, a clear inhibition of leucocyte migration after addition of antigen could be observed (maximum 16 h after addition of antigen). In 16 unsensitised controls no significant migration inhibition appeared. Possible advantages of this method over in vitro methods and intracutaneous tests are discussed.