The effects of recombinant interleukin 4 (IL-4) on cell cluster and multinucleated giant cell (MGC) formation from human immunodeficiency virus (HIV)-infected and uninfected monocytes were examined. Human blood monocytes were isolated by centrifugal elutriation and monoclonal antibody-complement-dependent lysis of residual T cells, and infected with low passage HIV strains. Monocytes were exposed to recombinant IL-4 (1 to 20 ng/ml), continuously after inoculation with HIV. Monocyte expression of ICAM-1 but not LFA-1 was significantly enhanced by IL-4 although substrate adherence was a more potent stimulus. Monocyte cluster and MGC formation was quantified after fixation and staining with Giemsa. Clusters of HIV-infected and uninfected monocytes were consistently and significantly increased at 4 to 7 days after IL-4 stimulation. The combination of HIV and IL-4 was more stimulatory than either treatment alone. In two out of five uninfected and three out of seven HIV-infected monocyte cultures, MGC formation was also markedly increased at 10 to 14 days after stimulation. Incubation with anti-LFA-1 (anti-CD11a, anti-CD18) and anti-ICAM-1 (anti-CD54) monoclonal antibodies reduced IL-4-stimulated aggregation in HIV-infected and uninfected monocytes and subsequently reduced MGC formation. Anti-ICAM-1 was not as effective as anti-CD11a or anti-CD18 in inhibiting aggregation of HIV-infected monocytes and in these cultures anti-ICAM-2 was also inhibitory. Extracellular HIV antigen concentrations were not consistently reduced by anti-CD11a or anti-ICAM-1. Hence IL-4 markedly enhanced monocyte aggregation in both HIV-infected and uninfected monocytes, probably through enhanced LFA-1-ICAM-1 interactions in all cultures and LFA-1-ICAM-2 interactions in infected monocytes, leading subsequently to MGC formation in some cultures.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error