Isotypic profiles and other fine characteristics of immune responses to exogenous thymus-dependent and -independent antigens by mice with lupus syndromes

The authors have now analyzed several aspects of immune responsiveness in SLE strains, compared with age- and allotypematched normal controls, to thymus-independent class 1 and 2 (Tl-1,2) antigens as well as to thymus-dependent (TD) antigens. Results indicate that all SLE strains are hyperresponsive to both TD and TI antigens and that their immunoglobulin (Ig) isotypic and IgG subclass profiles are different from those in normal strains; in general, an expansion of IgG2 subclass antibodies was observed. Moreover, NZ mice acquired immune competence with respect to Ti-2 antigen earlier than the other strains tested. Some, but not all, SLE strains sustained IgG immune responses to TI-2 antigens for longer periods than normal strains, whereas the avidities of antibodies produced in all SLE strains resembled those of their normal counterparts.