The contribution of the antimicrobial activity of sIgA, lactoferrin, α-lactalbumin, serum albumin, and lysozyme to the total antimicrobial activity of serum was evaluated. 66 breast milk samples from healthy women aged from 23 to 45 years collected at different periods of lactation were studied. It was found that as the lactation period increased, not only the total antimicrobial activity (r = - 0.944) decreased, but also the activity of the low molecular weight fraction containing the sum of antimicrobial peptides (r = - 0.950). The median lactoferrin level varied from 3.46 mg/ml in colostrum to 0.94 mg/ml one year after the onset of lactation and correlated with serum activity (r = 0.616). The concentration of sIgA was maximal in the serum of colostrum (5.01 mg/ml) and significantly reduced in mature milk, remaining approximately at the same level in subsequent periods of lactation (1.0 mg/ml). Serum albumin concentration significantly decreased with increase of lactation period (from 5.52 to 4.68 mg/ml) and correlated with serum activity (r = 0.589). Evaluation of the effect of the purified α-lactalbumin on C. albicans cells in the range of 5-20 mg/ ml by spectrophotometry and microscopy showed the absence of fungicidal activity. At the same time, purified lactoferrin, IgA, lysozyme, and serum albumin demonstrated a direct fungicidal effect. The activity of the IgA preparation at a concentration relevant to the sIgA content in the serum of first day colostrum was 50.0%, and in the serum after 12 months - 31.0%; lactoferrin - 26.7% and 3.4%; serum albumin - 15.0% and 17.7%; lysozyme - 0.1% and 1.8%. Thus, the sum of the activities of these polypeptides at concentrations typical for the first-day colostrum was 91.7%, which is comparable to the total activity of this serum - 82.4%. The sum of the activities of these polypeptides, typical for 12 months of lactation, was 53.9%, and the total serum activity relevant to this period was 64.5%. Therefore, IgA and lactoferrin contribute the most significant antimicrobial activity in the serum of colostrum, whereas after 12 months of breastfeeding IgA and serum albumin become most significant.

We evaluated the effect of vaccination with anti-COVID-19 vaccine EpiVacCorona on serum antimicrobial activity, formation of specific IgG antibodies, and expression of some antimicrobial peptides. Antimicrobial activity of the serum from 55 volunteers towards S. aureus cells was measured spectrophotometrically; IgG-antibodies against SARS-CoV-2 antigen were assayed by ELISA; expression of genes encoding antimicrobial peptides LL37, HBD1, and HBD2 was evaluated by PCR with reverse transcription. Total antimicrobial serum activity and activity of its low-molecular-weight fraction containing antimicrobial peptides demonstrated an inverse correlation. Both activities after vaccination increased in case of low initial values, but decreased in case of high initial values. The vector of change of specific IgG antibodies to coronavirus inversely correlated with the vector of change of activity of antimicrobial peptide fraction. The expression of genes of antimicrobial peptides LL37, HBD1, and HBD2 looked like normal distribution depending on activities of the antimicrobial peptides in the corresponding sera.

Антимикробные пептиды и белки (АМПБ) – это эндогенные соединения, оказывающие прямое противомикробное действие на бактерии, а также на грибы и вирусы. АМПБ являются основным компонентом врожденного иммунитета живых организмов и вырабатываются как эпителиальными клетками (клетки кожи, дыхательных путей, кишечника, мочевыводящих и половых путей), так и клетками иммунной системы, и выделяются в секреторные жидкости. Помимо антимикробной функции АМПБ могут выполнять роль хемоаттрактантов иммунокомпетентных клеток (нейтрофилы, моноциты, Т лимфоциты, дендритные клетки) в очаг воспаления. АМПБ оказывают влияние также на антигенпрезентирующие клетки, модулируя адаптивные T-клеточные иммунные ответы. Из большого количества описанных АМПБ наиболее изученными являются 15 основных классов, которые мы рассматриваем в данном обзоре, включая их локализацию, экспрессию и концентрацию в различных биожидкостях в норме и при патологии.

Antimicrobial peptides and proteins (AMPs) are endogenous compounds that have a direct antimicrobial effect on bacteria (e. g., by disrupting bacterial membranes), as well as on fungi and viruses. AMPs are the main component of the innate immunity of living organisms and are produced by both epithelial cells (skin cells, cells of respiratory tract, intestine, urinary and genital tracts) and cells of the immune system and are secreted into secretory fluids. AMPs can also act as chemoattractants for immunocompetent cells (neutrophils, monocytes, T lymphocytes, dendritic cells) in the inflammation site and affect the antigen presenting cells by modulating adaptive T cell immune responses. The representatives of the main 15 AMP classes, that we describe in this review, are the most studied group of the large pool of these compounds. We discuss their localization, expression, and concentration in various biofluids of humans under normal and pathological conditions.

Relevance. The introduction of Varicella vaccine prophylaxis explains the need to develop a methodology for monitoring the vaccination effectiveness and the intensity of population immunity. This problem can be solved using quantitative immunoassay methods. Aim. Development of an enzyme-linked immunosorbent assay for the concentration of class G immunoglobulins (AB) to Varicella zoster virus (VZV) determining and assessing its functional characteristics and diagnostic efficiency. Materials and methods. Recombinant antigen GE VZV. WHO International Standard for Antibodies to VZV W1044. Blood serum samples from healthy people and patients with Chickenpox and Herpes zoster, blood serum samples containing IgG antibodies to herpes simplex viruses of the first and second types, cytomegalovirus, Epstein-Barr virus. Anti-VZV ELISA (IgG) reagent kit (Euroimmun, Germany). Indirect enzyme-linked immunosorbent assay. Immunization of animals with recombinant antigen GE, isolation, and purification of specific antibodies. Conjugation of monoclonal antibodies to human IgG with antibodies to antigen GE and with horseradish peroxidase. Results. An enzyme-linked immunosorbent assay in «an indirect» format has been developed to determine the specific antibodies to VZV concentration (IU/ml) in human serum/plasma. An artificial calibrator for determining the concentration of AB-VZV had been synthesized and standardized according to the International WHO-standard W1044. The main functional characteristics of the developed enzyme-linked immunosorbent assay are determined in accordance with GOST 51352-2013. The diagnostic kit was tested on blood serum samples from children with chickenpox (n = 43), adults with Herpes zoster (n = 158), healthy individuals (n = 781). The diagnostic sensitivity of the test system was 85%, the diagnostic specificity was 87% according to the ROC analysis. The absence of cross-reactivity of the test system was shown on samples with serological markers of other herpesvirus infections (n = 94). Comparative trials of the developed test system and its commercial analog, the Anti-VZV ELISA (IgG) reagent kit, did not reveal statistically significant differences between their functional characteristics. Conclusions. The developed test system for determining of the AB-VZV concentration in human serum/plasma in terms of its functional characteristics meets the GOST requirements, is characterized by high diagnostic efficiency, can be used to monitor the effectiveness of vaccine prophylaxis and strength of population immunity, as well as to assess the immune response in chickenpox and Herpes zoster.