CD4+ T-Lymphocyte Level as a Predictor of Seroimmunity Strength to Tetanus in Adults Living with HIV

Vaccination is the main healthcare measure to control infectious diseases. People living with HIV (PLHIV) are at greater risk of beсoming ill or developing complications from vaccine-preventable infectious diseases. Tetanus is the most striking example of such an infectious pathology. Objective — to determine the level of seroimmunity against tetanus and assess the impact of the level of CD4+ T-lymphocytes on the intensity of anti-tetanus immunity in PLHIV to determine optimal vaccination regimens. Materials and methods. 90 PLHIV were involved in the study, the average age was (40.1 ± 0.9) years. Determination of the levels of anti-tetanus antibodies was carried out by the enzyme immunoassay method using the RIDASCREEN Tetanus IgG diagnostic test system (R-Biopharm AG, Germany). CD4+ quantitative content of T-lymphocytes was determined using the flow cytometry method with monoclonal antibodies. Statistical processing was performed using the Statistica v. 6.1 licensed software. Results and discussion. The research has shown that the median of anti-tetanus antibodies in PLWH was 0.59 (0.28—1.09) IU/mL. The unprotected cohort of PLHIV encompassed 52.2 % (n = 47). We have seen that restoration of the level of CD4+ T-lymphocytes in the context of antiretroviral therapy does not lead to «restoration» of specific antitoxic immunity. A reliable direct correlation was established between nadir of CD4+ T-lymphocytes and the degree of intensity of anti-tetanus immunity — rs = 0.42 (p < 0.001). According to the results of the ROC analysis, it was found that a high risk of lack of immunity against the specified infectious pathology is predicted in case of the decrease of nadir level of CD4+ T-lymphocytes less than 106 cells/μL (test sensitivity — 88.6 %, specificity — 52.9 %, diagnostic efficiency of the criterion — 71.0 %). Conclusions. The nadir level of CD4+ T-lymphocytes ≤ 106 cells/μL according to the result of ROC-ana­lysis indicates the absence of seroimmunity in PLHIV against tetanus, which justifies booster administration of tetanus toxoid. Clinicians and the public health system must organize effective strategies, including effective communication with PLHIV and social services, to effectively implement vaccine prevention goals.