Cellular requirements for lipopolysaccharide adjuvanticity. A role for both T lymphocytes and macrophages for in vitro responses to particulate antigens.

By employing primary cultures of purified spleen cells from lipopolysaccharide (LPS) responder (C3H/HeN or C57BL/10Sn) or nonresponder (C3H/HeJ or C57BL/10ScN) mice incubated with particulate antigen and LPS prepared by phenol-water extraction (Ph), we have presented evidence that both T cells and macrophages (MO) are required for LPS-induced adjuvanticity. First, MO derived from C3H/HeN spleen cells, when mixed with responder, C3H/HeN lymphocytes and Ph-LPS, elicited enhanced antibody responses to sheep erythrocytes (SRC) antigen, whereas lymphocytes from the nonresponder, C3H/HeJ mouse strain did not evoke this response. Similarly, purified T cells from C3H/HeN spleens, when cultured with responder, nu/nu spleen cells, and Ph-LPS yielded enhanced anti-TNP PFC responses; whereas, C3H/HeJ T cells did not potentiate immune responses when mixed with optimal concentrations of Ph-LPS. LPS prepared by butanol-water extraction elicited significant adjuvant effects with all cell combinations. Finally, purified responder T cells and MO enabled either responder or nonresponder B cells to elicit LPS potentiation. These data indicate that T cells and MO are controlling LPS-induced augmentation of B-cell responses.