Blood, Vol. 92 No. 11 (December 1), 1998:
pp. 4230-4237
Immunophenotypic Analysis of Peripheral Blood Mononuclear Cells
Undergoing In Vitro Apoptosis After Isolation From Human
Immunodeficiency Virus-Infected Children
Thomas W. McCloskey,
Saroj Bakshi,
Soe Than,
Parisa Arman, and
Savita Pahwa
From the North Shore University Hospital-New York University School
of Medicine, the Department of Pediatrics, the Division of
Allergy/Immunology, Manhasset, NY.
Lymphocytes of human immunodeficiency virus (HIV)-infected
individuals undergo accelerated apoptosis in vitro, but the subsets of
cells affected have not been clearly defined. This study examined the
relationship between lymphocyte phenotype and apoptotic cell death in
HIV-infected children by flow cytometry. Direct examination of the
phenotype of apoptotic lymphocytes was accomplished using a combination
of surface antigen labeling performed simultaneously with the Tdt
mediated Utp nick end-labeling (TUNEL) assay. In comparison to live cells, apoptotic lymphocytes displayed an
overrepresentation of CD45RO and HLA-DR expressing cells, while CD28
and CD95 expressing cells were underrepresented. Lymphocytes expressing
CD4, CD8, and CD38 were equally represented in apoptotic and live
populations. When percent lymphocyte apoptosis follow- ing
culture was examined independently with lymphocyte subsets in fresh
blood, apoptosis was negatively correlated with the percentage of CD4
cells, but not with specific CD4 T-cell subsets. Although not
correlated with the percentage of total CD8 cells, apoptosis was
positively correlated with specific CD8 T-cell subsets expressing
CD45RO and CD95 and negatively correlated for CD8 T cells expressing CD45RA. These results provide direct evidence that a population of
activated lymphocytes with the memory phenotype lacking the costimulatory molecule CD28 are especially prone to undergo apoptosis. The findings related to CD95 expression in fresh and apoptotic cells
implicate Fas-dependent and Fas-independent pathways of apoptosis in
HIV disease in children.
