Distribution of the Human Immunodeficiency Virus Coreceptors CXCR4 and CCR5 in Fetal Lymphoid Organs: Implications for Pathogenesis in Utero

HIV entry into a cell requires the coordinate cell surface expression of CD4 and one of several chemokine coreceptors. Here we have examined the expression of the two most widely utilized HIV coreceptors, CXCR4 and CCR5, on various lymphoid tissues derived from the fetus. CXCR4 and CCR5 are differentially expressed on lymphocytes in different lymphoid organs, which may reflect the maturational and functional status of cells within the organ. The different levels of coreceptor expression on CD4+ cells in the various organs may directly affect the targeting of CXCR4- and CCR5-tropic strains of HIV toward different fetal lymphoid tissues during in utero infection.