Enhancement of HIV-1 gp41 binding to Raji cells by PWM, LPS, interferon-gamma and interleukin-6.

Based on our finding that HIV-1 gp41 independently of CD4 can bind to several proteins (gp41 binding protein: GBP) on the human T-cell line H9, B-cell line Raji and monocyte-cell line U937, we examined the effect of mitogens and cytokines on binding of gp41 to H9, Raji and U937 cells. Flow cytometry (FACS) analysis demonstrated that PWM and LPS, IFN-gamma and IL-6, but not Con A, IFN-alpha, -beta, -omega and IL-2, could increase gp41 binding to Raji cells. In controls, none of the regulators (IFN-alpha, -beta, -gamma, -omega, IL-2, IL-6, Con A, PWM, LPS) could modify the binding potential of H9 and U937 cells. Our data suggest that the expression of HIV-1 binding proteins is subject to regulation by PWM, LPS, IFN-gamma and IL-6 in the case of B-cells, while on T-cells and macrophages, the binding proteins may be constitutively expressed.