Increased frequency of homogeneous immunoglobulins in the sera of nude athymic mice with age

Abstract

Sera from aging nude athymic mice, their heterozygous littermates, and normal mice of the BALB/c and CBA background strains were investigated for the presence of homogeneous immunoglobulins (H-Ig) by agar electrophoresis, immunoelectrophoresis, and immunofixation. While both the normal CBA and BALB/c mice showed only a very low incidence and a late onset of H-Ig, the barrier maintained and even more so the conventionalized nude mice developed H-Ig in very high frequencies with age. The incidence curve of H-Ig in the heterozygous mice occupied an intermediate position between that for the nude mice and the mice of their background strains. Follow-up studies of 50 barrier-maintained nude mice demonstrated persisting H-ig in 46% and transient H-Ig in 20% of the cases. The percentage distribution of individual Ig isotypes among 320 H-Ig components from the sera of nude mice was 1, 17, 43, 19, 8, and 12 for IgA, IgM, IgG1, IgG2a, IgG2b, and IgG3, respectively. Of these H-Ig, 15% contained λ and 85% κ light chains. These findings stress the importance of the T immune system in the regulation of the heterogeneity of Ig and are compatible with the hypothesis on the crucial role of an impairment in the T system in the development of age-related Ig abnormalities, including idiopathic paraproteinemia.