Serum immunoglobulin isotype profile of viable and non viable lymphoid cell chimaeras made with nude athymic lpr (lymphoproliferation) mouse recipients.

C57BL/6 mice (B6) which are homozygous at the nu (nude, athymic) and Ipr (lymphoproliferation) locus (B6 nulpr) are short-lived. We showed previously that increased survival could be obtained by grafting lymphoid cells from euthymic /pr-homozygous B6 mice (B6 Ipr) mice ([Ipr → nulpr] chimaeras), but curiously enough not from normal (B6 wild) mice ([wild → nulpr] chimaeras). Moreover female, but not male, [Ipr→ tnulpr] chimaeras developed spleen and lymph node enlargement. In the present paper the distribution and absolute concentrations of all serum immunoglobulin (Ig) isotypes have been determined in these chimaeras and their controls. All chimaeras displayed whole serum Ig levels higher than those of B6 wild mice, suggesting a successful reconstitution of the athymic recipients by the grafted lymphoid cells, but two types of chimaeras were peculiar. The short-lived [wild → nulpr] chimaeras showed a proportion of IgM as high as ungrafted B6 nulpr mice, suggesting a deficient down-regulation of IgM produc...