Strain- and age-associated differences in lymphocyte phenotypes and immune responsiveness in C4-deficient and Albany strains of guinea-pigs.

Spleen lymphocytes from C4-deficient (C4D) and Albany strains of guinea-pigs, 1-7 days, 3-6 and 12-16 months old, genetically related to inbred strains 13 and 2 respectively, were analysed in terms of their expression of cell surface markers, allogenic and T- and B-cell mitogenic responses, and interleukin-1 (IL-1) and IL-2 production. There were strain- and age-associated differences in phenotypic expression and immune responsiveness levels. In both strains a significant shift in immunocompetence apparently occurs postnatally before 3-6 months of age, with no further significant changes noticed in animals 12-16 months old. Phenotypic changes in cell surface markers did not always correlate with functional capability of lymphoid cells. H159+ (pan T) and H155+ (CD4) lymphocyte number and levels of T-cell responsiveness (mitogenic and allogenic responses, and IL-2 production) were higher in C4D neonates compared with age-matched Albany guinea-pigs or with young animals of the same strain. On the other hand, 31D2+ (B) lymphocytes in a significantly higher proportion in Albany neonates compared with similarly aged C4D, did not correlate at this age or at any other time with their proliferative response to lipopolysaccharide (LPS) or dextran sulphate (DS), two B-cell-specific mitogens.