Antigens apparently nonimmunogenic for xid/Y mice cause the development of specific splenic plasmablasts and of fusion partners for SP2 cells giving hybridomas that secrete antibodies.

Although xid/Y mice fail to make a detectable primary antibody response to a variety of antigens such as Type III pneumococcal capsular polysaccharide (SIII), 2,4, 6-trinitrophenyl (TNP)-Ficoll, pneumococcal C carbohydrate, group A streptococcal vaccine and several kinds of related antigenic determinants such as phosphorylcholine (PC) and N-acetyl-glucosaminyl (GlcNAc), even when the latter are coupled to hemocyanin (Hy), they do show: (a) an antigen-dependent development of splenic B cells which can act as successful, productive fusion partners for SP2 cells giving hybridomas making monoclonal anti-SIII, anti-PC, anti-GlcNAc, anti-TNP, etc., and (b) an antigen-dependent appearance of antigen-binding plasmablasts in their spleens. The frequencies of specific B cells arising in xid/Y males with either of these properties are of the same order of magnitude as those found in immunocompetent xid/X female littermates.