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In addition to the subsets of T lymphocytes and innate lymphocytes (innate lymphoid cells), the well-known players in adaptive immunity, there is an intermediate group of lymphocytes (innate-like cells) that already possess the T cell receptor, but with a restricted repertoire. This group includes γδT cells, subsets of type I and II NKT cells carrying both T cell receptor and NK-cell receptors, and mucosal-associated invariant T (MAIT) cells. The development of innate-like cells occurs in the thymus, but their positive and negative selection takes place without the participation of thymic epithelial cells. A distinctive feature is that innate-like cells acquire an effector phenotype already in the thymus, and therefore do not require complex activation reactions during antigen recognition. Upon exit from the thymus, noncanonical T cells express chemokine receptors, allowing them to migrate into barrier tissues at an early age. A characteristic feature of the T cell receptor innate-like cells is the recognition of non-peptide antigens presented in non-polymorphic histocompatibility molecules (MHC-Ib). This type of molecule includes the CD1 a/b/c/d/e molecule and the MR1 molecule. These molecules present lipid, glycolipid antigens and metabolites of B vitamins, synthesized by various representatives of the microbiota. The presence of functionally different subpopulations of innate-like cells with an activated phenotype allows them to quickly respond to the antigen by producing cytokines typical of Th1, Th2, Th17. They also exhibit cytotoxic and immunoregulatory activity. These cells are actively involved in regulation of barrier tissue homeostasis and interaction with microbiota. They synthesize growth factors for epithelial cells, fibroblasts, and vascular endothelium, which are required for regeneration of damaged tissues. They also participate in anti-infectious defense, directing the development of the immune response. Moreover, they have been found to be involved in many autoimmune diseases. The special functions of innate-like cells make them a promising target for therapeutic interventions. It has been shown that antibiotics, salicylates and some other well-known drugs exert certain effects on the innate-like cells. Different dietary options also affect the activity of these cells.

Most techniques for evaluation of T-cell immunity are laborious and unsuitable for routine laboratory diagnostics, thus encouraging researchers to look for accessible and reproducible tests. The purpose of our study is to compare three methods aimed for evaluation of cellular immune response levels to the SARS-CoV-2 viral antigens in patients who have been ill and vaccinated against a new coronavirus infection. We have examined 26 persons who experienced mild or moderate COVID-19 (group 1); 19 people vaccinated twice with Sputnik V, who did not have clinical COVID-19 (group 2); 21 subjects who had COVID-19 and were twice vaccinated with Sputnik V (group 3), and 14 persons who had COVID-19 twice (group 4). Peripheral blood mononuclear cells were isolated by gradient centrifugation. The first tested technique was performed as follows: the mononuclear cells were incubated with the S-protein of the SARS-CoV-2 virus, and stained with fluorescently labeled antibodies. The percentage of CD8highCD107a was counted by means of BD FACS Canto II flow cytometer. When assessed by the ELISpot method with “Human IFN-γ ELISpot” kit, IFNγ production was stimulated by SARS-CoV-2 S-protein, or a mixture of SARS-CoV-2 protein peptides in the “Corona-T-test” kit. There were no significant differences in the levels of CD107a expression on CD8high cells between the groups 1, 2, 3, and 4, as well as in amounts of IFNγ producers against SARS-CoV-2 S-protein when using “Human IFN-γ ELISpot” kit. Production of IFN was significantly lower in group 3 (hybrid immunity), i.e., 317.29±19.04 pg/ml compared to groups 1 and 2 (post-infection and post-vaccination immunity), i.e., 454.95±20.32 and 470.77±26.24 pg /ml, respectively. The relative level of IFNγ -producing cells in group 2 was higher (22.34±3.77) versus 16.83±2.35 in group 1, and 15.46±1.83 in group 3, whereas the relative levels of IFNγ did not differ in these groups. Stimulation with full-length S-protein showed a significant reduction in the number of spots in group 4 (breakthrough immunity), i.e., 30.59±2.29 vs 58.97±4.47 in group 3. Stimulation with a mixture of SARS-CoV-2 peptides in group 4 vs group 3 revealed a significantly increased number of IFNγ -producing cells (86.72±7.20 versus 69.38±5.53) and higher IFNγ production (991.25±65.18 pg/ml versus 760.76±50.70 pg/ml). Appropriate relative values were as follows: 10.30±2.77 versus 8.61±2.66, and 68.10±9.41 versus 48.35±8.15, respectively. The results of three methods for evaluation of cellular immune response correlate positively with each other, but at different significance levels.

Psoriasis is a chronic autoimmune skin disease with affected T-cell immunity. The interleukin IL-23/IL-17/IL-22 cytokine axis is a key to immunopathogenesis of psoriasis. Certain role of the IL-36 subfamily is shown in regulation of skin inflammation. Topically applied preparations are used to treat psoriasis. Our aim was to evaluate the treatment-related changes in the cytokine profile of venous and capillary blood collected close to the foci of psoriatic inflammation. Forty patients with psoriasis (mean age, 43.7 years), were examined. Group 1a (20 people) received local treatment with Mometasone, Group 1b (20 people) received topical gel containing an IL-36 receptor antagonist. Twenty healthy people (mean age, 46.6 years) comprised the control group 2. 200-μL aliquots of capillary blood were collected in a microvette with EDTA from the patients’ finger near to the lesion area. Venous blood (3 mL) was taken from the cubital vein to a vacuum tube with EDTA. The concentration of 15 cytokines in blood plasma was tested by the multiplex method (MagPix, BioRad, USA). Clinical effectiveness of therapy was assessed using the PASI and DLQI indexes. Upon completion of treatment (day 14), the PASI and DLQI indices were significantly decreased in both groups. On the 28th day, the PASI index in Group 1a returned to its original level, in group 1b it remained permanently reduced. Before treatment, the levels of all cytokines, except of IL-10, were significantly increased in capillary blood samples of patients with psoriasis compared to Group 2, and the levels of five cytokines were increased in the venous blood. In group 1a, the levels of IL-1, IL-4, IL-6, IL-21, IL-22, IL-23, IL-25, IL-33 were significantly decreased in capillary blood after 14 days, and only IL-17F, IL-21, IL-33 and TNF showed a decrease in the venous blood specimens. On the day +28, the concentrations of almost all cytokines returned to their original level. In Group 1b, on the 14th day, the levels of IFNγ, IL-1, IL-4, IL-17F, IL-21, IL-22, IL-23, IL-25, IL-33 were significantly decreased in capillary blood compared to altered IFNγ, IL-21, IL-22, IL-23, IL-33 in venous blood. On the 28th day, their concentration continued to decrease, or the level of these cytokines remained reduced, along with significant decrease of IL-6 in venous samples. Thus, the method for determining cytokine profile in capillary blood from the area of psoriatic lesions may be used for tracing the effects of therapy in psoriatic patients.

Psoriasis is considered an autoimmune disease with a predominantly cellular mechanism for the development of disorder. Studies in immune pathogenesis of psoriasis were performed either in animal model, which is not just similar to humans, or the data were obtained in patients by means of skin window method, which is traumatic, or by examining venous blood. However, it is difficult to discern parameters of the local immune response in venous blood samples. We have attempted to find an adequate method which would be convenient both for the patient and for the researcher, in order to assess local immune processes occurring in the skin affected by psoriasis. We examined 20 patients with a verified diagnosis of psoriasis, the average age was 44.3 years. The control group included 15 healthy adults, with average age of 46.6 years. Capillary blood was taken by fingerprick, whereas, in psoriatic patients, the samples were taken near the psoriatic lesion at a final volume of 400 μL in two microvettes. Venous blood (3 mL) was taken from the cubital vein into a vacuum tube with EDTA. Clinical analysis of venous and capillary blood was performed in automated hematological analyzer. Immunophenotyping was performed by four-color staining of whole capillary and venous blood followed by lysis of erythrocytes. Cytofluorometry was performed using techniques and reagents from BD Biosciences (USA). Plasma cytokines were determined by multiplex approach (MagPix, BioRad, USA). Upon clinical analysis of blood, the difference between capillary and venous blood was not found, either in healthy group, or among patients with psoriasis. In healthy people, the subsets of mononuclear cells, did not differ between venous and capillary blood. The samples of capillary and venous blood in the patients with psoriasis showed significantly increased levels of double-positive lymphocytes (CD45RA+/CD45R0+), B lymphocytes and NKT lymphocytes (both for relative and and absolute values). A significant increase in the percentage of naive T lymphocytes, activated helpers (Thact) and Treg, as well as B1 cells and Breg, and a significant decrease in B2 lymphocytes was registered in capillary blood of the patients with psoriasis. In venous blood samples from psoriatic patients, only a significant increase in Thact, Treg, and Breg was revealed. In the capillary blood of patients with psoriasis, we found a significant increase in the levels of non-classical M2 monocytes and inflammatory Minfl monocytes, and a decrease in classical M1 monocyte levels; in venous blood of psoriatic patients, only an increase in inflammatory Minfl monocytes was revealed. In capillary blood, all the studied cytokines in psoriasis patients significantly exceeded the levels of corresponding cytokines in healthy controls, except of IL-10. The levels of this cytokine did not differ from healthy group. In venous blood, the levels of most studied cytokines in the group of patients with psoriasis did not differ from the group of healthy ones. Approximately two-fold increase was revealed for IL-4, IL-21, IL-23 and TNF. First, the subsets of mononuclear cells and the cytokine profile of capillary and venous blood of healthy people did not differ significantly. Secondly, our proposed method for determining the subsets of mononuclear cells and capillary blood cytokines profile from the area of psoriatic lesions may be used to monitor local immunity in the patients with psoriasis. This approach is significantly less traumatic than the skin window method and more informative than the studies of venous blood.

The new coronavirus SARS-CoV-2 has become a global challenge to medicine and, in particular, laboratory diagnostics. The study of the antibodies’ level to SARS-CoV-2 can be used as a confirmation test in the diagnosis of a disease, but it becomes of paramount importance in assessing population immunity resulting from a disease or vaccination, as well as in selection of convalescent plasma donors. The kits developed in our country and abroad for detecting antibodies to the SARS-CoV-2 virus differ both in the methods of testing and in the used coronavirus antigens to which the antibodies are directed. The aim of this study was to compare the diagnostic sensitivity and specificity of five kits for the detection of IgG antibodies to the SARS-CoV-2 virus, based on different diagnostic methods. Serum samples from 137 COVID-19 convalescents and 166 donors of blood and its components were examined. The control group consisted of 50 blood sera collected at the beginning of 2019 and 19 sera collected in 2018 (before the advent of the SARS-CoV-2 virus) and stored at -70 °C. Testing was carried out in analytical systems: rapid test “COVID-19 IgM/IgG Rapid Test (Colloidal Gold)” (China), on an automatic immunochemical analyzer Abbott Architect™ i2000 and kit “SARS-CoV2-IgG” (Abbot, Chicago , IL USA), by the chemiluminescence method using an automatic analyzer of the CL series and kits of the “Mindray” company (China) “SARS-CoV-2 IgM” and “SARS-CoV-2 IgG” and by the enzyme immunoassay method on the kits of the companies “Diagnostic Systems” Ltd (Russia, Nizhny Novgorod) “DS-IFA-ANTI-SARS-CoV-2-G”, “Xema” Ltd (Federal State Budgetary Institution “National Medical Research Center of Hematology” of the Ministry of Health of Russia) “SARS-CoV-2-IgG-IFA” and “Vector-Best” CJSC (Russia, Novosibirsk)” SARS-COV-2-IgM-IFA-BEST” and “SARS-COV-2-IgG-IFABEST”. When comparing the results of testing 137 plasma samples on the Vector-Best and Mindray kits for IgG antibodies, 127 samples were positive, 7 samples were negative on both kits, the discrepancy was 2.2%. In the study of IgM antibodies, 32.1% were positive, and 52.6% were negative in both kits. The discrepancy rate was 15.3%. Out of 166 samples, 1 serum (0.6%) was negative in 5 kits. On the Mindray kit, IgG antibodies to the antigens of the SARS-CoV-2 virus were detected in 165 samples (99.4%), on Vector-Best – in 164 sera (98.8%), on Diagnostic systems – in 151 (90.96%), on Xema – in 154 (92.8%), and on Abbott – in 155 samples (93.4%). At the same time, 135 (81.33%) samples were positive in all kits, while 30 samples had discordant results (18.07%), and in 9 sera, specific IgG was not detected in 2 or more kits. ROC analysis revealed a high diagnostic value of all tested kits (AUC from 0.908 to 0.998), which indicates a high quality of the separation model of positive and negative samples (p < 0.001). With the cut-off set by the manufacturers, the sensitivity and specificity ranged from 82.8% and 93.3% for the Diagnostic Systems kit to 99.4% and 95.8% for the VectorBest kit. The calculated correlation coefficients were higher between kits with a similar composition of the antigen used in the kits; therefore, it is better to monitor the dynamics of antibodies by diagnostic kits from the same manufacturer.

Introduction. The implementation of the WHO Measles Elimination Program has yielded serious results, but in recent years an increase in the incidence rate of this infection has been observed. In particular, according to the WHO, in 2019 vs. 2018 measles morbidity was elevated by 3-fold worldwide. While investigating measles outbreaks among patients, apart from unvaccinated subjects, a substantial group of adults vaccinated in childhood was distinguished. The aim of this work was to examine the characteristics of humoral measles immunity in adult measles patients as well as subjects after measles vaccination. Materials and methods. 50 adult measles patients aged 20 to 55 years were examined. In all patients, the diagnosis was confirmed clinically and by laboratory assays by detecting measles IgM antibodies. The second group consisted of 50 conditionally healthy seronegative age-matched adults, vaccinated with the live measles vaccine (Microgen, Russia). Peripheral blood samples were collected from the cubital vein in total volume of 4 ml on 6±1 day after the onset of rash in patients as well as 6 weeks after vaccination. Specific measles antibodies and their avidity were determined by ELISA using the commercial Avidity: Anti-Measles Viruses ELISA/IgG kit (Euroimmun, Germany). Results. It was shown that people aged 20—35 years more likely suffered from measles than elderly. And it was in this age group that healthy measles seronegative individuals were more abundant. Among vaccinees, 44% responded to vaccination with the primary type of immune response, and 56% responded with the secondary type, while among measles patients, 34% and 66% responded with the primary and secondary type, respectively, as follows from the spectrum of specific IgG subclasses and the antibody avidity assay. The secondary type of immune response indicates that these subjects were apparently vaccinated against measles in childhood, but lost with time long-lived plasma cells producing protective antibodies. While comparing the parameters of specific humoral immunity in groups with acute measles infection (day 6 from the onset of rash) and early convalescents (3 weeks after the onset of rash), it was shown that the level of specific IgG increased threefold in early convalescents (p < 0.01) compared with those at acute phase. The level of specific IgA, on the contrary, decreased from 73.44 (69—75.3) Me/ml to 48.64 (45—56.4) Me/ml, but remained very high. At the same time, the spectrum of specific IgG subclasses shifted from primary immune response (high IgG3 and low IgG1) to secondary response (low IgG3 and high IgG1), which is typical for the response of emerging memory B cells.

B cell stimulation develops upon vaccination, thus causing occurrence of activated B cells (plasmoblasts) in bloodstream. Similar cells are also observed in some viral infections. The contents of plasmablasts may be a marker of successful vaccination, or a diagnostic feature of ongoing infection. The plasmablasts are normally represented by a small cell subpopulation which is not easy to detect. A study was performed with 15 healthy volunteers who were subjected to a single immunization with a recombinant vaccine against hepatitis B virus. To identify the plasmablasts, we have used labeled antibodies prepared in our laboratory. These reagents were previously validated for counting the plasmablasts. Different gating strategies for plasmablast gating have been compared. Upon staining of lymphocytes from immunized volunteers, we observed a distinct cluster of plasmablasts with CD27++CD38++ phenotype using the following antibody set: CD19-PE, CD3/CD14/CD16-FITC, CD27-PC5.5 and CD38-PC7. Inclusion of a CD20-FITC antibody into the panel caused an increase of CD27++CD38++ plasmablast ratio among CD19+ lymphocytes to > 60%. Upon substitution of CD38 antibody by anti-CD71, a distinct plasmablast cluster was again revealed, which contained ca. 5 per cent В cells. Two strategies for the plasmablast gating using the CD27/ CD38 and CD27/CD71 combinations were compared in dynamics with lymphocyte samples from a single vaccinated volunteer. When applying the CD27/CD38 combination, a sharp and pronounced plasmablast peak was registered on day 7 post-vaccination. With CD27/CD71 combination, the peak was extended between day 7 and day 14 following immunization. Hence, time kinetics of the CD27+CD71+ population proved to be different from occurrence of classic plasmablasts with CD27++CD38++ phenotype. This finding suggests that the CD27++CD71+population contains both plasmablasts and other types of activated B cells. A minor HBV surface antigen was prepared and labeled with phycoerythrin (HBsAg-PE), thus allowing to quantify the antigen-specific plasmablasts. The results of HBsAg-PE-based detection of antigen-specific cells were in compliance with the data obtained by ELISpot technique. At the present time, we use the original plasmablast gating technique for detection of activated B cells in SARS-CoV-2 infection. At the next step, this technique will be applied to sorting of antigen-specific B cells, thus permitting sequencing of Ig genes and design of novel human antibodies against viral antigens.B cell stimulation develops upon vaccination, thus causing occurrence of activated B cells (plasmoblasts) in bloodstream. Similar cells are also observed in some viral infections. The contents of plasmablasts may be a marker of successful vaccination, or a diagnostic feature of ongoing infection. The plasmablasts are normally represented by a small cell subpopulation which is not easy to detect. A study was performed with 15 healthy volunteers who were subjected to a single immunization with a recombinant vaccine against hepatitis B virus. To identify the plasmablasts, we have used labeled antibodies prepared in our laboratory. These reagents were previously validated for counting the plasmablasts. Different gating strategies for plasmablast gating have been compared. Upon staining of lymphocytes from immunized volunteers, we observed a distinct cluster of plasmablasts with CD27++CD38++ phenotype using the following antibody set: CD19-PE, CD3/CD14/CD16-FITC, CD27-PC5.5 and CD38-PC7. Inclusion of a CD20-FITC antibody into the panel caused an increase of CD27++CD38++ plasmablast ratio among CD19+ lymphocytes to > 60%. Upon substitution of CD38 antibody by anti-CD71, a distinct plasmablast cluster was again revealed, which contained ca. 5 per cent В cells. Two strategies for the plasmablast gating using the CD27/ CD38 and CD27/CD71 combinations were compared in dynamics with lymphocyte samples from a single vaccinated volunteer. When applying the CD27/CD38 combination, a sharp and pronounced plasmablast peak was registered on day 7 post-vaccination. With CD27/CD71 combination, the peak was extended between day 7 and day 14 following immunization. Hence, time kinetics of the CD27+CD71+ population proved to be different from occurrence of classic plasmablasts with CD27++CD38++ phenotype. This finding suggests that the CD27++CD71+ population contains both plasmablasts and other types of activated B cells. A minor HBV surface antigen was prepared and labeled with phycoerythrin (HBsAg-PE), thus allowing to quantify the antigen-specific plasmablasts. The results of HBsAg-PE-based detection of antigen-specific cells were in compliance with the data obtained by ELISpot technique. At the present time, we use the original plasmablast gating technique for detection of activated B cells in SARS-CoV-2 infection. At the next step, this technique will be applied to sorting of antigen-specific B cells, thus permitting sequencing of Ig genes and design of novel human antibodies against viral antigens.

In 2010—2016, blood serum samples were examined from 5539 patients, aged < 1—60 years, with clinically and laboratory confirmed measles. Primary or secondary type of immune response was determined for all measles cases. Studies were performed with children aged < 1—14 years (2381), adolescents, 15—17 years old (189), and adults aged 18—60 years (2969). Serum measles-specific IgM antibodies were measured by “VektoKor’ IgM” ELISA test system (Russia), concentration and avidity of specific IgG — by using “Anti-Measles Viruses ELISA/IgG” and “Avidity: Anti-Measles Viruses ELISA/ IgG” (Euroimmun, Germany). Primary immune response was identified based on the presence of serum measles-specific low avidity IgM and IgG antibodies, whereas secondary immune response was characterized by detecting high avidity IgM and IgG antibodies at concentration of ≥ 5.0 IU/ml. Analyzing measles-specific IgM antibodies in 2010—2016 demonstrated that measles morbidity was mainly due to children, aged 1—2 years reaching up to 39.9% of the total number of children with measles aged < 1—14 years as well as adults aged 18—40 years old comprising as high as 80.1% total number of patients aged 15—60 years. Serum measles-specific IgG testing showed that in 15.0% of cases they were detected at concentration of ≥ 5.0 IU/ml. Further serum dilution resulted in finding IgG titer ranging within 8.5—45.0 IU/ml (21.4+0.36) and high avidity antibodies in 80—100% (92.5+0.2) cases. The remaining 85.0% cases found low avidity measles-specific IgG antibodies (< 30%) at concentration of 0.2—3.46 IU/ml (1.73+0.03). An age-related analysis of our data demonstrated that all children under 14 with laboratory-confirmed measles developed primary immune response. Moreover, in 73.7% of measles patients aged 15—60 with primary immune response measles might be prevented by timely vaccination, whereas persons with “vaccine failure” comprised 26.3%. In 2010 (0.09 per 100,000 subjects) and 2016 (0.12 per 100,000 subjects), frequency of patients with “vaccine failure” during relative epidemic well-being was 35.3% and 18.2%, respectively, exceeding 9.9% (p < 0.001) serving as a hallmark 2014 high measles incidence rate (3.24 per 100,000 subjects).The data obtained indicate that measles virus circulate among people with “vaccine failure,” which may account for potential to spread and infect unprotected population cohorts as well as cause measles outbreaks during periods of epidemic well-being.

Inflammatory bowel diseases (IBD), such as Crohn’s disease (CD) and ulcerative colitis (UC), are characterized by chronically recurring inflammation of intestinal wall and are associated with a significant decrease in the quality of life. A spectrum of genetic variants associated with Crohn’s disease is described. Intestinal dysbiosis (DB) may be the triggering factor of the disease. Glycoprotein 2 (GP2), the main protein of pancreatic zymogen granules, is secreted into the intestines with digestive enzymes. Anti-GP2 antibodies were found in the serum of patients with CD. The aim of the present study was to investigate the levels of anti-GP2 antibodies in serum and feces of children with IBD compared with the DB group. Serums and coprofiltrates from 110 children (64 boys and 46 girls) at the age of 12.3 (2.6-17.9) years were studied; 36 patients with CD, 30 patients with UC. A comparison group consisted of 44 patients with DB. IgG and IgA antibodies against GP2 were tested with ELISA. Nonparametric statistics methods are applied, the results are presented as percentages and medians (Me (Q0.25-Q0.75)). The serum levels of anti-GP2 IgA antibodies were 9.97 (3.35-13.45) U/ml for the CD patients, 6.08 (2.71-14.26) U/ml for UC and 2. 94 (2.29-6.41) U/ml for DB. The levels of anti-GP2 IgG antibodies in serum were 6.16 (3.26-18.4) U/ml for CD, 5.26 (2.97-7.52) U/ml for UC, and for DB 5.23 (2.53-8.85) U/ml. The cut-off threshold concentration for anti-GP2 IgG antibodies was 13.8 U/ml, with sensitivity of 63.2%, specificity 100%, and for IgA 5.63 U/ml, with sensitivity of 60.5% and specificity of 78.8%, thus being lower than the calculated cut-off for adults (20 U/ml). The levels of anti-GP2 IgG in coprofiltrates in children of comparison group were 1.99 (1.26-3.04) U/ml; in the patients with CD, 23.5 (16.15-29.3) U/ml, and in children with UC, 20.45 (13.63-25.5) units/ml (p < 0.001). The cut-off value amounted 8.0 U/ml, with 100% sensitivity and 100% specificity. Concentrations of anti-GP2 IgA in coprofiltrates of patients with IBD did not significantly differ from DB patients. Moreover, the concentration of sIgA in the coprofiltrates of patients with IBD was significantly higher than their level in DB group. The anti-GP2 IgA/sIgA ratio was significantly lower in patients with CD (0.326 (0.23-0.512)), and UC (0.327 (0.205-0.435)), than in patients with DB (2.332 (1.575-3.523)) (p < 0.001); the cut-off level was 0.784, with a sensitivity of 97.7% and specificity of 98.6%. It is discussed, whether fecal anti-GP2 IgA antibodies should be considered as protective, supporting intestinal homeostasis, whereas anti-GP2 IgG antibodies are pathogenetically significant for development of IBD. Thus, using a non-invasive method for determining anti-GP2 antibodies in stool, when exceeding the cut-off for IgG, and reduction of IgA/sIgA ratio below the cut-off, one may differentiate IBD from DB with a similar symptoms at the onset of disease, with 100% sensitivity and 100% specificity.

Immunological memory and tolerance represent major achievements and advantages of adaptive immunity. Organisms bearing adaptive immunity display prominent competitive advantages in the fight against infections. Memory immune cells are preserved for decades and are able to repel a second attack of an infectious agent. However, studies performed in the XXI century have shown that even unrelated pathogens may be quickly and effectively destroyed by memory cells. This type of response is called heterologous so that heterologous immune response is mainly typical to viral infections and other intracellular infections, where T-cells play a lead role in protection. This review will discuss various mechanisms involved in implementing T-cell cross-reactivity, describe molecular prerequisites for heterologous T-cell responses. Experimental evidence of memory T-cell potential to heterologous immune response in mouse models and in human infections are also discussed. Heterologous immune response is an important immune arm in adults and the elderly when the yield of naive cells to the periphery declines due to thymus involution. Along with obvious advantages, heterologous immune response leads to imbalanced memory T-cell repertoire, replacement of immunodominant epitopes with minor ones allowing viruses to evade immune response that results in virus persistence, or, conversely, fulminant infection course. Another threat of heterologous immune response due to switch in dominant repertoire of recognizable epitopes is presented by random self-epitope recognition, which can lead to development of autoimmune pathology. Heterologous immunity can also disrupt drug-induced tolerance in organ and tissue transplants and lead to graft rejection. Heterologous immune response should be taken into consideration while developing and using new vaccines, especially in adults and the elderly.

Despite adherence to the policy of mass measles vaccination in the majority of countries, this infection still remains far from being fully eradicated. Measles outbreaks are reported worldwide, when the vast majority of cases are recorded in subjects of 18—35 years of age. Studies on assessing measles IgG antibody level in different regions of Russia reveal increased percentage of measles seronegative subjects among young adults. Current study was aimed at investigating formation of humoral and cellular immunity after measles vaccination in seronegative adults aged 18 to 30 years old. There were enrolled 50 measles seronegative healthy volunteers aged 18 to 30 years old. Level of anti-measles IgM and IgG antibodies was measured by ELISA (Vector-Best, Russia). Subclasses of measles specific IgG antibodies were analyzed by ELISA, by replacing IgG conjugate for IgG1, IgG2, IgG3, IgG4 conjugates, whereas measles specific IgA antibodies were estimated by ELISA with IgA conjugate (Polygnost, Russia) at a concentration of 1 μg/ml. Antibody avidity was assessed by ELISA (Euroimmun, Germany). Cell-mediated measles immunity was estimated by CD107a surface expression on CD8hi T cell subset stimulated by measles virus-derived antigens. A specific cellular response to measles antigens before vaccination was detected in 50% of examined subjects, whereas 40% samples showed no signs of cellular immune response, with 10% of remaining cases described as equivocal. It was found that 6 weeks after vaccination all vaccinated subjects developed measles specific IgG antibodies at protective level reaching 1.33 (0.85—1.82) IU/ml [Me (LQ—UQ)]. Anti-measles IgA antibodies were of 0.655 (0.423—1.208) IU/ml [Me (LQ—UQ)]. However, no measles specific IgM antibodies were detected 6 weeks after vaccination. In addition, primary type of immune response (dominant low-avidity anti-measles antibodies IgG3 subclass) to measles vaccination was observed in 24 out of 50 subjects, whereas 26 subjects developed secondary type of immune response (high-avidity anti-measles antibodies dominated by IgG1 subclass). A measles specific cellular immune response was observed in 47 of the 50 examined subjects, and in 3 volunteers it was equivocal. Further analysis revealed a cohort of subjects who were not vaccinated against measles (18 subjects), although 60% of them provided medical record on previous dual measles vaccination occurred in childhood. Another cohort consisted of subjects who had medical record of measles vaccination in childhood (32 subjects), but lost protective measles antibodies produced by plasma cells (23 subjects), and memory T cells (3 subjects), or measles antibodies and memory B cells (6 subjects) over time. Such pattern evidences that measles-specific cellular and humoral arms immune responses were developed and maintained independently of each other.

The interleukin-36 (IL-36) family was discerned in the superfamily of interleukin-1 (IL-1) ten years ago. This family includes three isoforms of IL-36α, IL-36β, IL-36γ, which have pro-inflammatory activity and a specific receptor antagonist, IL-36ra, which implements anti-inflammatory function. All of them bind to the same IL-1R6 receptor. The pro-inflammatory isoforms also involve an accessory IL-1RAcP protein into signaling; resulting into conduction of a signal into the cell via the assembling heterodimer receptor. In contrast, IL-36ra inhibits the formation of a heterodimer and blocks the signal transmission. The cytokines of the IL-36 family and appropriate receptors are normally expressed on epithelial cells in barrier tissues such as the respiratory, intestinal tract and skin. Like all cytokines of the IL-1 superfamily, IL-36 is synthesized as inactive form and requires activation, but not due to caspases, but being mediated by neutrophil enzymes, such as cathepsin G, proteinase-3, and elastase, which are constantly present in barrier tissues. In this regard, IL-36 is involved in homeostasis of barrier tissues. Apparently, the IL-36 cytokine system appeared in response to the developing ability of some microorganisms to avoid immune recognition and activation of innate immune response, and, in particular, the IL-1 pro-inflammatory system. An imbalance between the pro- and anti-inflammatory pathways readily causes inflammation in the corresponding tissue. This review discusses participation of cytokines from the IL-36 family in homeostasis of barrier tissues, as well as potential role of the IL-36 family in pathogenesis of bacterial, viral, and fungal skin diseases, atopic dermatitis, autoimmune diseases, such as rheumatoid arthritis, systemic lupus erythematosus, Sjogren's syndrome, ulcerative colitis and Crohn's disease. The role of IL-36 family cytokines in the immunopathogenesis of psoriasis has been well studied. This review is presenting the modern ideas about immune pathogenesis of psoriasis. The special role of cytokines from the IL-36 family was shown both for induction of psoriatic inflammation and evolving a positive feedback loop that supports and enhances the immune component of inflammation, which leads to progression of the disease. Moreover, modern methods of treating psoriasis are discussed, in particular, a possible promising approach to IL-36 blockade, or usage of recombinant IL-36ra for the treatment of psoriatic patients. Experimental studies in this area in mice provide some grounds for optimism.

An issue of eradicating measles and rubella virus-induced infections currently remains unresolved, despite existing effective methods for specific prophylaxis and WHO’s commitment to a mass vaccination policy. While improving epidemic situation, analysis of new challenges, such as measles incidence in adults, especially in adults vaccinated in childhood, is of particular interest. The aim of the study was to analyze serum measles and rubella virus-specific IgG antibodies in young healthy people and estimate antigen-specific cellular immune response in seronegative subjects. There were examined 100 healthy adults aged 18–30 years old. Level of serum specific IgG was measured by ELISA (Vector-Best, Russia). Antigen-specific cellular immune response was assessed by magnitude of surface CD107a expression on CD8hi T cells challenged by measles and rubella virus-derived antigens. It was found that average level of antibodies against rubella virus comprised 175.5 IU/ml, 49% of which recovered after rubella, 46% were vaccinated, whereas 5% subjects contained no virus-specific antibodies. In addition, mean level of anti-measles virus antibodies was below protective magnitude, among which 1% subjects recovered after measles, 31% displayed post-vaccination immunity, 55% subjects were seronegative, and 13% had equivocal levels of specific antibodies. Thus, 68% subjects were unprotected against measles virus based on the level of serum virus-specific antibodies. Moreover, 40 out of 68 subjects were vaccinated against measles in childhood. Additional screening adult subjects for intensity of measles and rubella virus-specific cellular immunity demonstrated that 57.37% of them contained peripheral blood CD8 T cells against measles virus and 59.01% — against rubella virus. Further analysis allowed to identify 4 subgroups displaying: 1) high level of virus-specific antibodies and T cells; 2) neither antibodies nor specific T-cells reaching as low as 20% of baseline group; 3) high antibody level combined with low amount of specific T cells; and 4) low antibody level combined with high level of specific T cells. thus, it may be assumed that cellular and humoral immune arms are maintained independently and being active for a long term after vaccination. Preserving a specific T-cell immunity seems to provide protection against infection, thereby accounting for the lack of measles manifestation in all seronegative subjects.

According to the lasting serological investigations of patients with rubella and measles, a major factor that determines the resistance to the infections is specific antibodies, that are still circulating in blood of recovered persons during their life. Since vaccinated people are also included in this concept, serological monitoring of people different ages who get vaccinated against rubella and measles is conducted in Russia. However the discrepancy between specific immunity intensity and the measles incidence was showed last years. Using “Vector Best” kits, the study of the anti-measles and antirubella population immunity in scale of age: under 1 year, 1–2 years, 3–6 years, 7–14 years, 15–17 years, 18–30 years, 31–40 years, 41–50 years, and 51–60 years was carried out in Moscow and Moscow region in 2013 (period of unfavorable epidemic situation). The serum probes were obtained from 654 random healthy donors and 646 patients with serologically confirmed measles infection. As a result, gradual increase of percentage of people with protective antibodies to rubella and measles have been demonstrated: 81.3% donors aged 7–14 years were protected from measles and more than 90% — from rubella. Moreover, percentage of individuals who have had immunity to rubella were the same in adults too. The most marked increase of percentage of seronegative persons to measles virus (40% and more) was in age from 18 to 30 years, and in groups over the age 40 years old protection reaches 85–95%. Comparison between percentage of measles patients different ages and percentage of persons with protective antibodies in serum have demonstrated significant negative correlation between measles prevalence and the level of specific antibody in population (r = –0.76). According to the results, increase (to 28%) and decrease (to 2.9%) of measles patients aged 18 to 30 and 51 to 60 years are based on decrease (to 55%) and increase (to 95%) of persons with protective immunity, respectively. Results of analysis of measles prevalence in different ages have demonstrated, that among adult measles patients (18–50 years) 14.5% responded on infection by secondary immune response; among children and teenagers there were no such patients, that proves the significant effectiveness of prophylactic vaccines.

(IBD), who were for the first time treated with TNFα blocker (infliximab). Our aim was to determine prognostic informative value of the immunological parameters in order to assess the treatment efficiency. A comprehensive research included seventy children with IBD from 12 to 18 years old in the course of specific treatment (49 children with CD, 21 children with UC).The comparison group consisted of fifty healthy children of similar age who were subjected to a similar detailed examination. The patients were divided into two groups, depending on their therapeutic response following 1 year of biological therapy: the first group showed a persistent positive effect of the drug, and the second group exhibited only unstable effects of the treatment. We determined the contents of major and small subpopulations of peripheral blood lymphocytes before the first administration of infliximab. Immunophenotyping was performed by multicolor flow cytometry (FC 500), using the CD45, CD3, CD4, CD8, CD19, CD16, CD56, HLA-DR, CD5, CD161, CD127, CD25, and CD294 markers.We have revealed that the content of B lymphocytes was significantly reduced in children with unstable effects of therapy. By contrast, the B lymphocyte levels in children with persistent positive therapeutic effect did not differ from the comparison group. Analysis of the composition of the B lymphocyte profile showed an imbalance in the B1-to-B2 cell ratio, with decreased of B1 cell counts in IBD patients against the comparison group. In addition, the patients with unstable therapeutic effect showed a significant decrease in B2 cell numbers compared with a group with persistent effect and comparison group. The numbers of NK cells in IBD patients were found to be reduced against the comparison group. Assessment of T lymphocytes subsets revealed a number of features in the patients with minimal therapeutic effects, i.e., an increased level of activated T helper cells (CD4+CD25+CD127high) and Th17 lymphocytes (CD3+CD4+CD161+), as compared to children with stable effect of treatment and to the comparison group. Moreover, in children with minimal effects of therapy, the levels of Tregs within T-helper cell subsets were significantly higher than in the comparison group. By means of ROC analysis, we have identified most informative parameters for the groups with minimal versus persistent therapeutic effect, and showed a good quality for a discrimination model involving relative amount of Th17 cells, activated T helper cells and B lymphocytes. The number of Тh17 lymphocytes (% CD3+CD4+ lymphocytes) allowed to predict the effect of therapy with a TNFα blocker with high probability. The present study enables us to propose cellular immunity testing, as a promising tool for monitoring clinical state of IBD patients.

Age-dependent development of Th17 and Treg lymphocyte subsets in healthy humans is studied insufficiently. The present study aimed to investigate quantitative characteristics of Th17 and Treg subsets in peripheral blood of healthy subjects for various age groups.352 healthy humans (168 female and 184 male), one month to 85 years old, were subject to examination, including 79 infants in their first year of life; 34 children at aged 1 year to 2 years 11 months; 24, at 3 to 4 years 11 months; 28, at the age of 5 to 6 years 11 months; 25 children aged 7-8 years 11 month; 36 children aged 9 to 11 years 11 months; 39 adolescents aged 12 to 14 years 11 months; 26 adolescents aged 15 to 18 years; 25 young adults aged 20 to 35 years; 11 adults at 36 to 49 years old; 16 adults aged 59-70 years, and 9 elderly people over 70 years old. The study was performed with capillary blood in children under 2 years, and venous blood taken in elder persons. The basic and ‘minor’ subsets of peripheral blood lymphocytes were evaluated by flow cytometry using four-color staining of whole blood and following erythrocyte lysis. We used the following surface markers: CD3, CD4, CD8, CD25, CD127, CD161, CD45R0 for lymphocyte subsets detection.It has been shown that Treg percentage (a ratio of CD4+CD25hiCD127low/neg in the CD3+CD4+ gate) did not depend on age of the people under study, and can be approximated by a linear function. The absolute number of Tregs in childhood is progressively decreased and, after 10 years old, it reaches plateau values. This age-dependent relationship may be approximated by a logarithmic function. Evaluation of Th17 subset levels demonstrated a strong relative and absolute age-dependent growth of this cell subpopulation. Percentage and absolute numbers of Th17 lymphocyte (share of CD4+CD161+CD45R0+ in the CD3+CD4+gate), can be approximated by a square function. The age of 10-12 years seems to be critical to the immune system formation. We suppose the process of the immune system development to be completed at this age, and maturation of the immune cell populations is then observed. A decrease in both relative and absolute numbers of Treg and Th17 lymphocyte subsets was found in elderly persons (> 70 years old). Our data on peripheral blood Tregs and Th17 subsets, with respect to their percentage and absolute numbers in healthy humans, may be used as age-related reference values.

Abstract. The immune status and the level of specific antibodies to Cytomegalovirus (121 patients) or Mycoplasma pneumoniae (129 patients) were tested in 250 patients aged 19–56 years old. This cohort was divided for three groups. Seventy eight patients with low level of CD3+CD4+ lymphocytes and normal rates of other parameters of immune status were jointed in Group 1. The second group was presented by 85 patients with low level of CD3+CD4+ and high level of CD3+CD8+ lymphocytes. Eighty seven patients with lymphopenia were distinguished in Group 3. All patients were treated with antiviral or antibacterial and immunomodulatory drugs. Three schemes of immunomodulatory therapy including imunofanum, polyoxidonium, cycloferonum, glutoxim, immunomax in different combination were used. In three weeks after treatment in 72,4% of patients no clinical symptoms as well as normalization of immune status indices and decrease of specific antibodies titers were observed. Sixty nine patients reported improvement of subjective health status, however they had high level of specific antibodies. Immunological examination of these patients after second course of immunomodulatory therapy confirmed their convalescence. It was shown that the condition of immune status determines effect of the different immunomodulators.

Abstract. The aim of study was to investigate peculiarities of specific immune responses in vaccinated and unvaccinated measles convalescents. Twelve infants with natural measles infection at 5–7th day after onset of rash (Group 1), 14 adults with natural measles infection at 5–7th day (Group 2), 13 adults with measles at 12–15th day after onset of rash (Group 3), and 15 measles patients previously vaccinated against measles (Group 4) were examined. Fifteen healthy adults had twodose measles vaccination at 1 year and 6 years old (Group 5), and 17 healthy adults had measles many years ago (Group 6) were included in the study as a control groups. Specific IgM, IgA, IgG antibodies in serum, and their subclasses and avidity were tested by ELISA. High level of specific IgM and IgA-antibodies, and increasing of low-avidity IgG-antibodies, predominantly IgG3 subclass were typical for the humoral immune response in unvaccinated patients. On the contrary, lower level of IgM and the highest level of specific IgA and high-avidity IgG, predominantly IgG1 subclass characterized the group of previously vaccinated measles patients. The humoral immune response in vaccinated volunteers was characterized by lower level of specific IgA, IgG and avidity than in adults had measles in their childhood (group 6). The laboratory plays a critical role in case classification when rash and fever develop in persons who have possibly been exposed to measles. Waning of measles antibody, however, does not necessarily equate to waning immunity, because B-memory cells responses can increase of the antibody synthesis.

Abstract. T follicular helper cells (Tfh) are a CD4+ Th cell subset promoted the cognate control of antigen-specific B cell immunity. Upon first contact with antigen-primed B cells, Tfh can support either extrafollicularly differentiation into short-lived plasma cells (PC) or enter follicles to form germinal centers (GC). Signaling lymphocytic activation molecule (SLAM) interaction between Tfh and activated B-cells is essential for GC development. Within GC, Tfh regulates the fate of antigen-specific GC B cells expressing high-affinity B cell receptors to develop memory B cell (Bm) or long-lived PC. Short-lived PC produce low-affinity IgM and IgG3 early antibodies. Both Bm and long-lived PC have high-affinity class-switched IgA and IgG, predominantly IgG1 antibodies. Measles virus uses human SLAM-molecule as a cellular receptor. SLAM is expressed on dendritic cells and activated B and T-cells. This is an important regulator of the isotype switching and antibody affinity maturation, especially IgG3-IgG1 switching. Development of long-term humoral immunity, charac terized by the formation of high-affinity predominantly IgG1 antibodies, is a critical component of protective immunity to pathogens and the major goal of vaccination. However, the mechanisms involved in the shaping and sustaining of long-term humoral immunity remain poorly understood.

Abstract. Twenty healthy children were vaccinated, and then in a 5 years they were revaccinated with Priorix (measles, mumps, rubella vaccine), according to the national immunization calendar. The aim of the study was to observe and compare the shaping and maintenance of immunological memory. Specific IgM, IgA, IgG antibodies in serum, and their subclasses as well as antibodies avidity were tested by ELISA. It was demonstrated that IgM, IgG, and IgA antibodies shaped primary immune response to Priorix. Booster-effect was found in IgG and IgA antibodies in response to revaccination. Low avidity of antibodies in primary immune response changed to the high avidity (60–70%) antibodies of memory response to measles and rubella, and remained low for antimumps antibodies. IgG3 subclass was predominant, and IgG1 and IgG4 subclasses were involved in primary immune response. At the stage of immunological memory IgG1 was predominanted and IgG3 and IgG4 became minor.

Abstract. Age dynamics of humoral immunity was studied in healthy children, i.e., 11 newborns, 33 infants of 4 to 8 months, 32 children of 1 to 2 years old,, 17 children of 4 to 5 years old, 25 children of 6 to 8 years old, 15 children of 9 to 11 years old, and 28 adolescents of 14 to 16 years old. Evaluation of membrane receptors on B cells was performed by means of three-colour fluorescent label and allowed of characterizing B1 subpopulations (CD19+CD5+CD27-), naпve B2 cells (CD19+CD5-CD27-), and B2 memory cells (CD19+CD5-CD27+). B1 cells have been shown to dominate in blood of newborns and younger children (up to 5 years old). By the contrary, B2 memory cells were nearly undetectable in newborns, and exceeded 20% in adolescents (by 15 years old). Meanwhile, it has been revealed that the amounts of IgG1 and IgG3 subclasses did progressively increase with age, whereas IgG2 remained decreased to 50% of adult values for a long time, and reached them by 11 years and later. We suggest that the age dynamics of IgG subclasses is connected with age-dependent changes in B cell subpopulations.