The expression of CD4 antigen on the surface of LeuM3-positive human blood monocytes was found to be variable with 65 to 90% of cells from 46 normal human volunteers being positive by dual staining flow cytometry. When monocytes adhered to plastic (but not when cultured on Teflon), a marked decrease in CD4 expression was observed between 1 and 24 h post-adherence. CD4 expression could not be detected in macrophages adhered to plastic for 5 days by using four anti-CD4 monoclonal antibodies in flow cytometry or direct immunofluorescence. Conversely an increasing proportion of adherent cells expressed LeuM3 and OKM5 surface antigens over the 5 days. CD4 mRNA levels were measured by slot-blot and Northern hybridization, and total cellular CD4 protein levels by immunoprecipitation. Both cellular mRNA and CD4 levels remained constant throughout the 5 day period but membrane CD4 protein levels were greatly reduced indicating that the down-regulation of CD4 was posttranslational. Infection with two of six fresh human immunodeficiency virus (HIV) isolates showed different kinetic patterns when tested on purified monocytes recently adhered to plastic and macrophages adherent for 5 days. HIV antigen and reverse transcriptase levels in infected monocyte cultures remained high for 3 to 4 weeks before detachment and necrosis of the cells occurred. Infection of macrophages generated much lower levels of antigen and reverse transcriptase which declined to very low or undetectable levels over 2 weeks, leaving persisting viable macrophages. One week after infection HIV nucleic acid was detected in 69 ± 7% of monocytes and 6 ± 3% of macrophages by hybridization. Blocking experiments with anti-Leu3a monoclonal antibody suggested that HIV infection of 5 day adherent macrophages occurred mainly by a mechanism other than binding to CD4.

Keyword(s): CD4 , HIV , macrophages and monocytes

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