CD4 EXPRESSION BY ERYTHROID PRECURSOR CELLS IN HUMAN BONE-MARROW

Flow cytometry was used to assess CD4 expression in 62 consecutive bon e marrow specimens from patients with a variety of clinical conditions . Using a lysed-whole-blood technique for labeling with monoclonal ant ibodies, two populations of CD4(+) cells were identified within the ly mphocyte/blast-cell fraction in 58 (94%) of these specimens. These con sisted of (1) a population of T helper cells with high-density express ion of CD4 and (2) a second population of cells with low-density expre ssion of CD4. which ranged from 1% to 36% of the gated cells. This lat ter population was present regardless of age. sex. or clinical conditi on including 21 of 21 specimens (100%) categorized as unremarkable bon e marrows both morphologically and by flow cytometry and in four of fo ur patients (100%) with human immunodeficiency virus-type 1 (HIV-1) in fection. Coexpression of the erythroid lineage marker, glycophorin A, with the majority of cells in this second population was demonstrated in all 11 randomly selected samples using two-color flow cytometric an alysis. These cells also expressed low levels of the myeloid markers. CD13 and CD33. but CD34 expression could not be demonstrated. These re sults provide evidence for expression of CD4 on cells of erythroid lin eage in human bone marrow, and offer a potential mechanism for direct infection of erythroid precursor cells and deranged erythropoiesis in patients with HIV-1 infection. (C) 1996 by The American Society of Hem atology.