Regulatory T Cell Counts and Development of Malignancy in Patients with HIV Infection

T-regulatory cells (Tregs) play an important role in maintaining homeostasis by attenuating the cytokine response to T-cell receptor (TCR) stimulation and by suppressing the functioning of neighboring immune cells. In Human Immunodeficiency Virus (HIV) infection, Tregs can be either beneficial, by suppressing generalized T-cell activation, or detrimental, by suppressing protective anti-HIV cell-mediated immunity. An imbalance of Tregs and effector T-cells can blunt immune responses to malignant cells or facilitate inflammation-mediated pathologies.

The purpose of our study was to explore the possible correlation between Tregs' concentration and HIV infection's parameters as well as the development of hematological and solid malignancies.

In a longitudinal prospective study, ex vivo phenotyping of fresh peripheral blood mononuclear cells from patients with primary HIV infection was performed at baseline. All patients were then followed up every 3 months and the development of solid or hematological malignancies was noted.

A total of 155 patients were included in the study and the median follow-up period was 64 months. Treg counts were significantly higher among males, patients with high viral load (>350 copies/ml) and patients with virological failure to antiretroviral treatment (ART). Linear regression analysis showed a significant negative correlation between Treg levels and CD4 (+) T-cell counts. Patients with neoplasia had lower levels of Tregs while increasing levels showed a negative correlation with the development of neoplasia.

In our population of HIV-infected patients, high levels of Tregs were associated with disease progression, and low baseline levels were associated with a higher probability of developing neoplasia.