THE NUMBER OF CD1A(-DENSITY CELLS WITH DENDRITIC CELL FEATURES IS INCREASED IN THE PERIPHERAL-BLOOD OF HIV+ PATIENTS() LARGE LOW)

Employing a discontinuous Percoll gradient following Ficoll-Hypaque se paration of peripheral blood mononuclear cells from normal subjects (n = 14) and patients with HIV-1 infection (n = 50), we separated a popu lation of low-density cells consisting of monocytoid cells, lymphocyte s, and some granulocytes. In cytospin preparations, less than 5% of th e monocytoid cells were positive for nonspecific esterase and CD14. Ho wever, CD1a was positive in 5-20% of these cells. Ultrastructurally, C D1a-labeled immunogold particles were demonstrated on the monocytoid c ells which bore some features of dendritic cells. Flow cytometry of th e low-density cells identified a subset of buoyant, large cell populat ion, which excluded lymphocytes. This large low-density cell (LLDC) po pulation was significantly expanded in patients with HIV infection and comprised 32.3 +/- 21.3% of low-density cells compared to 7.0 +/- 2.8 % in normal subjects (P < 0.0001). Of the LLDC population 45.2 +/- 23. 4% were CD1a(+) in patients compared to 17.5 +/- 13.3% in normal subje cts (P less than or equal to 0.0001). HLA-DR and HLA-DQ were coexpress ed in approximately 70 and 50% of these CD1a(+) LLDC, respectively. A simple nonculture assay method employed by us facilitates rapid screen ing of infected blood specimens for the CD1a(+) large low-density cell s with dendritic cell features, which could be an additional parameter to monitor HIV disease progression. (C) 1994 Academic Press, Inc.