Modulation of antigen-presenting capacity of human monocytes by HIV-1 GP120 molecule fragments.

The two fragments of HIV-1 gp120 molecule were synthesized to study their interaction with human monocytes. Previous observations indicated that recombinant gp120 fragment (aa residues 410-511) encompassing CD4 binding region (rp120cd) induced tumour necrosis factor alpha (TNF) production in monocytes, while a similar fragment (rp120) not containing the CD4 binding sequence (aa 446-511) was inactive. This paper shows that rp120cd depressed monocyte ability to present antigen (PPD) to autologous T lymphocytes while rp120 was noninhibitory. The rp120cd interacted with monocytes but not T lymphocytes. Anti-TNF receptor type A antibody (utr-1) prevented the depression of antigen presentation caused by rp120cd, which suggested a role for TNF and its receptor. The depression of antigen presentation was seen only when monocytes were treated with rp120cd before, but not after, pulse with antigen. Parallel changes were observed in PPD-induced IL-6 production. Thus, induction of TNF by gp120 may be associated with impairment of antigen-presenting capacity of monocytes seen in AIDS patients.