Surface expression of CD-4 does not predict susceptibility to infection with HIV-1 in human monocyte hybridomas

In contrast to T-cell lines, where CD-4 expression may predict susceptibility to HIV infection, in monocyte hybridomas, presence or absence of surface CD-4 does not appear to be the determining factor of susceptibility to HIV infection. One clone, 20, was documented to be CD-4 negative by surface immunofluorescence as well as by immunoprecipitation. Both CD-4+ and CD-4- human monocyte hybridomas, representative of peripheral blood monocytes were readily infected with HIV (strains IIIB and BR-1 and a variety of patient isolates) as assessed by p24 Ag secretion reverse transcriptase activity and in situ hybridization. Infection occurred in the absence of antibody to HIV suggesting a non Fc mediated process as had been previously described. These data suggest that alternative mechanisms, such as non-specific phagocytosis, may exist for entry of HIV into peripheral blood monocytes. Given these findings, treatment for AIDS, such as the use of soluble CD-4, may not be effective long term, as monocyte infection may still occur and serve as a reservoir for subsequent viral infection of T cells.