Suppression of immunological activities by mouse amniotic fluid.

Mouse amniotic fluid (MAF) was shown to be capable of suppressing those antibody responses observed in euthymic or athymic mouse spleen cell cultures to the T-independent antigens dinitrophenylated Ficoll (DNP-Ficoll) and trinitrophenylated lipopolysaccharide (TNP-LPS) and to the polyclonal B-cell activators LPS and purified protein derivative of tuberculin (PPD). Titration experiments demonstrated that the suppressive capacity of MAF for either LPS or DNP-Ficoll responses was maintained up to a MAF dilution of 1:120. Preincubation of spleen cells obtained from athymic mice with MAF for 8 h significantly suppressed polyclonal B-cell activation of such cells induced by LPS, although suppression was greater when MAF was present during the entire culture period. In addition, the suppressive activity that MAF demonstrated for antibody production induced by DNP-Ficoll or LPS was not lost as a result of dialysis. MAF also suppressed the secondary in vitro proliferative responses of lymph node cells sensitized to the T-dependent antigen human gamma globulin (HGG). HGG-induced proliferation of such cells appeared to be more susceptible to suppression effected by MAF than concanavalin-A-induced proliferation.