Preparation of human and murine monoclonal antibodies: antigens combined with or conjugated to lipopeptides constitute potent immunogens for in vitro and in vivo immunizations

Lipopeptide analogues of bacterial lipoprotein constitute polyclonal B lymphocyte activators. Combined with or covalently coupled to antigens, they act as potent adjuvants. We could show that antigens (BSA-DNP, TNP-SRBC, saxitoxin, HIV-1 gp160 (BH10^303–329), EGFR^516–523) combined with or coupled to the synthetic lipodipeptide N-palmitoyl-S-(2,3-bis(palmitoyloxy)-(2RS)-propyl)-(R)-cysteinyl-serine (P₃CS) constitute active immunogens in vivo in mice. They were also able to induce an in vitro humoral immune response in the murine and human systems, and B lymphocytes thus activated were suitable for fusion. Thus, the antigens chaperonin/phytochrome, BSA-saxitoxin, histamine, HIV-1 gp160 (BH10^303–329), HIV-1 gp160 (RF^316–341), and HIV-2 pl7 (ROD^111–121) combined with or conjugated to P₃CS could be used for in vitro immunization followed by the preparation of murine and human monoclonal antibodies. Our novel immunization procedure offers reproducibility, high antibody titers often after one immunization, lack of toxicity of the adjuvants, easy chemical preparation of the conjugates in mg amounts, and the applicability of the conjugates for screening for the antibodies obtained.