CD38-Expression-on-CD8-Cells and Its Influence-onDevelopment-of-Tuberculosis-in-HIV
Right from the stage of infection with HIV, most of the individuals exhibit perturbation of T cells and their subsets, leading to their exacerbation in the absolute number with time. These immune cell turbulences along with variation in their function lead to progressive immunodeficiency [1] resulting in an increased risk of opportunistic infections, such as tuberculosis. HIV infection is well recognized with highly variable disease progression rates between individuals and are categorized as rapid, intermediate and long-term non-progressors [2]. Lympho proliferative response to HIV-specific antigen is well established in long-term non-progressors than those with more rapid progression [2]. It is well-known that CD4+ cells decline during infection with HIV and the numbers reduce further with disease progression [3]. Reduction in the number of peripheral CD4+ T cells in patients with active tuberculosis also and restoration to normal counts after successful chemotherapy has been reported earlier [4]. The influence of CD8+ cells on progression of HIV disease is a concern, as cytotoxic T lymphocytes (CTLs) are responsible for specific cellular immune response [2]. Evidences of HIV infection in humans and nonhuman primate models indicate the role of CD8+ T cells in controlling or limiting HIV-1 replication [5]. Studies revealed that HIV-1 specific CD8+ cells are associated with nonprogressive HIV-1 infection [6].
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HIV is a virus spread through certain body fluids that attacks the body's immune system, specifically the CD4 cells, often called T cells. Over time, HIV can destroy so many of these cells that the body can't fight off infections and disease. These special cells help the immune system fight off infections. HIV weakens the immune system, increasing the risk of TB in people with HIV. Infection with both HIV and TB is called HIV/TB coinfection. Latent TB is more likely to advance to TB disease in people with HIV than in people without HIV. TB disease ,CD38 expression on CD8+ cells seems to correlate well with HIV viral-loads, while the expression levels are thought to be low in patients with tuberculosis. This study aimed at determining the levels of CD38 expression in HIV+ individuals who develop tuberculosis. Expression levels of CD8 and CD38 were analysed in peripheral blood collected from HIV (73), TB (32), HIV-TB (31) and healthy controls (20). The percentage of CD8+/CD38+ cells significantly increased during the first few years of seropositivity and decreased during 5 - 6 years. A decline in the expression of CD38, especially on CD8+ cells in a HIV+ individual within first 2 years of seropositivity, may be indicative of susceptibility to tuberculosis. This observation was reiterated when two patients developed TB during follow-up. CD38 on CD8 cells could perhaps be useful as an early biomarker for tuberculosis in HIV-positive individuals.
