Immunologic Targets of HIV Infection: T Cells^a

Abstract

One of the principal targets of HIV infection is the human peripheral blood CD4+ T cell, resulting in progressive CD4+ lymphocyte loss. Hypothesized mechanisms for this loss include apoptosis, cytolytic reactions, V-beta gene deletion of the T-cell receptor (TCR) by superantigens, CD4+ lymphocyte syncytium formation, and autoimmune reactions. In adults with HIV infection, the critical decline in CD4+ lymphocyte number that heralds the onset of AIDS-defining conditions is well characterized, whereas in infants and children the critical level of CD4+ cells predisposing to the development of AIDS-defining conditions or mortality is not fully characterized, due to an incomplete knowledge of CD4+ lymphocyte number and changes with age in normal and HIV-infected children. In a prospective study of 317 infants born to HIV-infected women, early results show that the monthly change in absolute CD4+ lymphocyte number over a 3- to 9-month period in HIV-infected infants was -109 cells/mm3 per month, at least double the rate of decline measured in HIV-noninfected infants in the study or that calculated from normal infants' values reported in the literature. In other clinical studies in HIV-infected infants and children, it was possible to study the effect of low CD4+ cell counts on clinical status and mortality. In HIV-infected pediatric patients younger than 1 year, it was possible to correlate low CD4+ cell number with advanced disease status (CDC pediatric class P-2). It was also possible to correlate extremely low CD4+ cell counts (< 200 cells/mm3) in HIV-infected children with a significant risk of mortality within the next 3 months of life. Sequential CD4+ cell analysis of HIV-high-risk infants will delineate the rate of HIV-related decline in CD4+ cells, thus facilitating the diagnosis of HIV infection and aiding in identification of HIV-infected children at high risk of disease progression or death.

Immuno-haematologic and virologic responses and predictors of virologic failure in HIV-1 infected adults on first-line antiretroviral therapy in Cameroon

“…Diminution of CD4 + T-cells and haematological complications are hallmarks of HIV disease progression [15] associated with increase morbidity and mortality [16]. The incidence and severity of these factors generally correlate with the stage of the disease with anaemia being the most common and important haematologic predictor of HIV progression to AIDS [17].…”

CD4+ T-Lymphocytes cell counts in adults with human immunodeficiency virus infection at the medical department of a tertiary health institution in Nigeria

“…[1,2] Depletion of CD4ϩ T cells is one of the hallmarks of progression of HIV infections. [3] The absolute CD4 cell count is used routinely in the evaluation and monitoring of HIV-infected persons. [4] CD4 cell counts have been found to have good correlation with development of various complications in HIV/AIDS.…”

Evaluation of Immune Survival Factors in Pediatric HIV‐1 Infection

“…A preliminary report of the immune function of the children enrolled in the National Institutes of Health National Heart, Lung and Blood Institute P 2 C 2 HIV‐1 Study recorded the measurements of CD4 + (helper) T cells and CD8 + (cytotoxic) T cells in HIV‐1 + children followed for less than 24 months of the 60‐month study. 1 Results of this study showed an early and continuing loss of CD4 + T cells through 17 months of age in HIV‐1 + children and an early rise at 2‐4 months followed by a decline of CD4 + T cells in HIV‐1 − children, although at 17 months the mean cell count was higher by 1,200 cells/μl. There was an expansion of the CD8 + T‐cell population, beginning as early as 2 months of age in some HIV‐1‐infected children and rising to 50% of the peripheral blood mononuclear cell population.…”