The Influence of CD4+ T-Lymphocytes on the Strength of Anti-Diphtheria Immunity in Adult People Living with HIV

Abstract

Vaccination is an important tool for preventing infectious diseases. People living with HIV (PLHIV) are a vulnerable group because they are at greater risk of contracting or developing complications from vaccine-preventable infectious diseases. Diphtheria is the most striking example of such an infectious pathology. Objective — to determine the level of seroprotection against diphtheria and assess the impact of CD4+ T-lymphocyte levels on the intensity of anti¬diphtheria immunity in PLHIV. Materials and methods. 90 PLHIV were involved in the study, the average age was (40.1 ± 0.9) years. Anti-diphtheria antibody levels were determined by enzyme-linked immunoenzyme assay using the RIDASCREEN Diphtheria IgG diagnostic test system (R-Biopharm AG, Germany). The quantitative content of CD4+ T-lymphocytes was determined using the flow cytometry method using monoclonal antibodies. Statistical processing was performed using the Statistica v. 6.1 license program. Results and discussion. The study revealed that the median level of anti-diphtheria antibodies in PLHIV was 0.17 IU/ml (0.09—0.38 IU/ml). The proportion of PLHIV without protection against diphtheria was 93.3 % (n = 84). A significant positive correlation was observed between the nadir of CD4+ T-lymphocytes and the strength of anti-diphtheria immunity (rs = 0.49, p < 0.001). ROC analysis indicated that a nadir level of CD4+ T-lymphocytes below 126 cells/µl predicts a high risk of lacking immunity against diphtheria, with a test sensitivity of 81.5 %, specificity of 100 %, and diagnostic efficiency of 82.6 %. Conclusions. The serological anti-diphtheria status of PLHIV is considered critically low. Assessment of the nadir level of CD4+ T-lymphocytes proved to be informative for determining the risk of immunological vulnerability of PLHIV against diphtheria. Since the increase in the level of CD4+ T-lymphocytes against the background of antiretroviral therapy does not lead to «restoration» of specific immunity, such PLHIV will need a booster administration of diphtheria toxoid.