CD4 mRNA accumulation is unaltered in HIV-1 infected monocytic cell lines depleted of cell surface CD4.
Int Conf AIDS 1990 Jun 20-23; 6:323 (abstract no. 1037) Geleziunas R, Bour S, Boulerice F, Wainberg MA; Jewish General Hospital and McGill University AIDS Centre, Montreal, Quebec, Canada
HIV-1 infection of cells expressing the CD4 glycoprotein generally leads to the reduction or disappearance of cell surface CD4. We have compared mechanisms of CD4 downregulation in HIV-1 infected monocytes with those in T-cells. We have analyzed both CD4 mRNA and protein levels in HIV-1 chronically infected monocytic cell lines: U-937, THP-1 and PLB 985. These chronically infected cell lines displayed decreased levels of cell surface CD4 as judged by flow cytometry using both OKT4 and Leu3a mAbs. Steady state CD4 mRNA levels were unaltered in these infected monocytic cells, in contrast to the decline of CD4 mRNA seen in infected lymphocytes. However, OKT4-immunoprecipitable CD4 protein levels were diminished in the infected U-937 cell line. In addition OKT4 co-precipitated viral gp120, suggesting that CD4-gp120 complexes are present in infected monocytes as well as lymphocytes. Reduced CD4 protein and CD4-gp120 complex formation are thus responsible for the absence of membrane-associated CD4 in HIV-1 infected U-937 cells. Hence, reduced CD4 gene expression is not a factor contributing to cell surface depletion of CD4 in HIV-1 infected monocytic cells. Our results suggest that a lymphoid cellular intermediate may be required to achieve reduced CD4 mRNA levels following HIV-1 infection.
Keywords: AEGIS, Antigens, CD4, HIV-1, Monocytes, Cell Line, RNA, Messenger, HIV Infections, HIV-1 Reverse Transcriptase, Down-Regulation, T-Lymphocytes, Cell Membrane, genetics, ICA6
