Isolation of HIV-1 from monocytes of individuals negative by conventional culture

To improve isolation of human immunodeficiency virus (HIV) from purified monocytic cell populations, a differential culture technique was applied to blood from HIV-seropositive individuals, culture-negative for HIV by routine culture. When 206 individuals were grouped by percentage of CD4⁺ lymphocytes, increases in viral isolation rates were significantly associated with declines in percentage of CD4⁺ cells (P <.0001). Of 158 asymptomatic individuals, 78% had >400 CD4⁺ lymphocytes/mm³. Only 19% were culture-positive using routine methods. Separation of peripheral blood mononuclear cells (PBMC) into purified lymphocyte and monocyte subpopulations for 12 asymptomatic patients and subsequent HIV culture of each purified subpopulation using three different indicator cell lines resulted in 100% virus recoveryfrom purified monocytes cultured in the U-937 promonocytic cell line. Culture of purified lymphocytes in U937 cells did not increase the isolation rate, whereas culture of patient PBMC in U-937 indicator cells and in allogeneic monocytes resulted in a 50% increase in mvisolation. A monocytic indicator cell line added to routine culture methods may improve virus recovery from asymptomatic individuals.