Immunoglobulin levels of congenitally athymic rats immunized with thymus-dependent-independent antigens.

The levels of immunoglobulins (Ig) in the serum and saliva of nude (rnu/rnu), congenitally athymic rats and control (rnu/+) rats were studied after injection in the vicinity of the salivary glands with several different T-dependent or T-independent dinitrophenylated antigens. Serum IgG levels were higher in rnu/+ rats than rnu/rnu rats after both primary and secondary immunizations. WHile serum IgM levels were higher in rnu/+ rats after primary immunization, secondary immunization with the most thymic-dependent antigens elicited higher IgM levels in rnu/rnu rats. After primary immunization, serum IgA levels in rnu/rnu rats were significantly lower than rnu/+ levels but no differences between the groups were noted after secondary immunization. Primary immunization with these antigens also demonstrated a markedly reduced salivary IgA producing capability by the athymic rats. Importantly, no such differences in serum or salivary IgA were previously found in the absence of immunization. Thus, immunization accentuated differences in Ig level and isotype distribution between rnu/rnu and rnu/+ rats.