Functional status of cells from lymphoid and myeloid tissues in mice with severe combined immunodeficiency disease.

Cells from mice with severe combined immunodeficiency disease (SCID) were tested in assays that measure myeloid and lymphoid function. Results showed that C.B-17 scid and their normal counterparts (C.B-17) have similar levels of spleen colony-forming units. The frequency of in vitro myeloid colony-forming units in C.B-17 scid spleen is elevated, but the absolute number of colony-forming units in C.B-17 scid and C.B-17 spleen is similar. The absolute number of bone marrow colony-forming units in C.B-17 scid and C.B-17 mice is comparable. Cells from C.B-17 scid spleen are consistently negative in all tests of B and T cell function. C.B-17 scid splenocytes fail to proliferate in response to T and B cell mitogens or to allogeneic lymphocytes in a one-way MLR; C.B-17 scid cells do serve as stimulators in MLR. B lymphocyte colony-forming units are absent, as are cytotoxic lymphocyte precursors and cells that can generate T cell colonies with cytotoxic progenitors. The microenvironment of the C.B-17 scid mouse is conducive to lymphocyte differentiation, because functional B and T cells are easily detectable in mice reconstituted with normal bone marrow cells. The results of this study indicate that scid specifically impairs the differentiation of stem cells into mature lymphocytes; myeloid cell differentiation is not affected.