B cell-driven HIV type 1 expression in T cells: an essential role of CD86 costimulatory molecule.

ABSTRACT During HIV-1 infection, HIV-1 is sequestered and actively replicates within lymphoid organs, mainly in areas essential for antigen-specific T–B interactions. We investigated whether cognate T–B interactions not only drive humoral response to HIV-1 but also enhance viral replication. Costimulation of in vitro HIV-1-infected tonsillar T cells with autologous or allogeneic activated B cells increased both viral replication and T cell proliferation. Addition of CD86 MAb to cocultures inhibited most p24 (84 ± 12%, n = 13) and IL-2 (99 ± 2%, n = 6) production, decreased T cell proliferation by 46 ± 15% (n = 13), and decreased TNF-α and IFN-γ production by 67 ± 17% (n = 6) and 53 ± 6% (n = 6), respectively. In contrast, CD80 MAb, which strongly inhibited IL-2 production (77 ± 10%, n = 6), moderately downregulated p24 and TNF-α production (29 ± 21%, n = 13 and 34 ± 10%, n = 6, respectively) and did not decrease T cell proliferation (8 ± 10%, n = 13) or IFN-γ production (14 ± 13%, n = 6). We thus showed t...