Cloned mouse cells with natural killer function and cloned suppressor T cells express ultrastructural and biochemical features not shared by cloned inducer T cells.

Abstract

The morphology, cytochemistry and biochemistry of mouse leukocyte subsets were examined by analyzing cloned leukocyte populations specialized to perform different immunologic functions. Cloned cells expressing high-affinity plasma membrane receptors for IgE and mediating natural killer (NK) lysis and cloned antigen-specific suppressor T cells contained prominent osmiophilic cytoplasmic granules similar by ultrastructure to those of mouse basophils. Both clones also incorporated 35SO4 into granule-associated sulfated glycosaminoglycans, expressed a characteristic ultrastructural pattern of nonspecific esterase activity, incorporated exogenous [3H]5-hydroxytryptamine and contained cytoplasmic deposits of particulate glycogen. Cloned inducer T cells lacked cytoplasmic granules and glycogen, incorporated neither 35SO4 nor [3H]5-hydroxytryptamine and differed from the other clones in pattern of nonspecific esterase activity. Certain cloned cells with NK activity and cloned suppressor T cells express morphologic and biochemical characteristics heretofore associated with basophilic granulocytes. These clones differ in surface glycoprotein expression and immunologic function, and the full extent of the similarities and differences among these populations and basophils remains to be determined. The ultrastructure of a long-term guinea pig cell line with alloreactive cytolytic T cell activity was examined. By EM, these cells represent lymphocytes with relatively abundant cytoplasm containing a few small, dense lysosomes. They do not resemble guinea pig basophils by morphology. The ultrastructure of functionally similar leukocytes maintained in vitro may vary considerably according to species.