CD3+ T cells in severe combined immunodeficiency (scid) mice VI. RESCUE OF SCID-DERIVED, IGM-PRODUCING B CELLS BY TRANSFER OF CD4+ CD8– T CELLS FROM VARIOUS LYMPHOID ORGANS.

Intravenous injection of purified CD4⁺ CD8^- T cells from thymus, spleen or lymph nodes of adult dm2 donor mice (H-2^d, L^d-, IgM^a) into young C. B-17 scid/scid (scid) mice (H-2^d, L^d+, IgM^b) partially and selectively reconstituted the splenic CD4⁺ T-cell compartment of recipient scid mice. This was demonstrated by cytofluorographic analyses, histological examinations, growing donor-derived CD4⁺ T-cell lines in vitro from spleens of transplanted scid mice, and serial passage of L^d-, CD3⁺ CD4⁺ CD8^- T-cell lines through young scid recipients for more than 1 year. Host-derived IgM^b appeared in sera of all CD4⁺ T-cell-transplanted young scid mice, while none of the sex- and age-matched, non-transplanted control scid mice was Ig⁺. B-cell leakiness was most efficiently induced by transfer of low numbers of adult CD4⁺ CD8^- thymocytes: transfer of 10³ purified CD4⁺ CD8 thymocytes efficiently rescued scid-derived B cells, while transfer of 2 × 10⁷ non-fractionated thymocytes from the same donor mouse was inefficient. Serum antibodies of scid mice with T-cell induced B-cell leakiness stained congenic 'double-positive' (CD4⁺ CD8⁺) thymocytes and immunoprecipitated protein bands with an apparent MW of 14,000, 28,000, 43,000, 65,000 and 80,000 from ¹²⁵I-labelled thymocytes. These data indicate that repopulation of peripheral lymphoid organs with CD4⁺ T cells is always accompanied by partial co-reconstitution of the B-cell system, and raises the question of the interdependence of these two lymphocyte subsets. [ABSTRACT FROM AUTHOR]