Developmental and communicative interrelations of Ly123 and Ly1 cell sets.

To distinguish and define the differentiative and communicative relations of Ly123 and Ly1 cells in generating specific helper-effector (HE) (Ly1:HE) and specific suppression-inducing (SI) (Ly1:SI) cells, these two functional sets were generated from various combinations of congenic genetically marked sets of cortisone-resistant nylon-purified thymocytes (CRNPT) by culture on antigen-primed macrophages (M phi) (the (T-M phi culture system). It was thus shown that Ly1:HE and Ly1:SI cells are produced by differentiation from antecedent Ly123 cells. Ly1:HE and Ly1:SI are separate Ly1 populations; generationof Ly1:HE cells requires the presence of Ly1 cells, whereas the generation of Ly1:SI cells does not. Although the Ly23 CRNPT set, which is included when Ly123 cells are positively selected with Lty-2 antiserum is ruled out as a precursor source of Ly1:SI cells, the possibility of a communicative role for Ly23 cells in generating Ly1:SI cells remains to be investigated. The role of the Ly1 set required for the generation of Ly1:HE cells from CRNPT is communicative, not differential; and it is not a precursor source of Ly1:HE or Ly1:SI cells in the CRNPT population. It remains to be seen whether the use of additional phenotypic markers will distinguish subsets of Ly123 and Ly1 cells engaged in these several functions.