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CBA/N mice harbour an X-linked B cell defect which is transmitted by CBA/N female mice to their hybrid male progeny. These mice mount normal responses to thymus-dependent (TD) and some thymus-independent (TI-1) antigens, while the response to TI-2 antigens is absent. Hapten-specific plaque-forming cell (PFC) responses to TD antigens can be blockaded by concomitant exposure of these mice to TI-2 antigens bearing the same hapten. This paper investigates in defective mice the blockade of their response to TNP3-LPS (trinitrophenylated lipopolysaccharide, a TI-1 antigen), imposed by DNP59-Ficoll (dinitrophenylated Ficoll, a TI-2 antigen). The effectiveness of the blocking agent, DNP59-Ficoll, differed in various inbred mouse strains: CBA/N × C3H/HeN F1 male > CBA/N female > CBA/N · C3H/HeN F1 female. The role of T cells in the observed hapten-specific blockade phenomenon was investigated using athymic CBA/N nude mice and a B cell tolerogen. Our findings indicate that T cell participation is not essential for the blockade of CBA/N PFC responses and they suggest that direct blockade of TI- and TD-responsive B cell populations is likely to occur. [ABSTRACT FROM AUTHOR]

CBA/N mice have an X-linked S-cell defect which prevents them from responding to non- mitogenic thymus-independent (T1-2) antigens such as haptenated Ficoll. The CBA/N mice do, however, respond to another group of thymus-independent (TI-2) antigens among which are haptenated liposomes. The F1 male progeny of CBA/N female mice express the same characteristics. Hapten-specific plaque-forming cell (PFC) responses to haptenated proteins (thymus-dependent, TD, antigens) by CSA/N mice and CBA/N × C3H/HeN F1 male mice can be blocked by concomitant exposure to TI-2 antigens bearing the same hapten. Simultaneous exposure to haptenated liposomes (TI- I antigen) and TD antigens, however, results in a synergistic response to the hapten if the antigens share common epitopes. The tripeptide-enlarged hapten dinitrophenyl-β-alanylgly- cylglycine (J), conjugated to phosphatidyl-ethanol- amine (PE) and incorporated into liposomal model membranes, was used throughout the experiments. In F1 male mice the moderate responses to TD antigens could be restored to values equivalent to those seen in F1 female mice. This adjuvant effect of haptenated liposomes is hapten-specific, time-dependent, and restricted to certain structural forms of the liposomes. [ABSTRACT FROM AUTHOR]