The generation of cytolytic activity in mixed leukocyte cultures: cortisone-resistant thymocytes are deficient in helper T lymphocytes.
Cortisone-resistant (CR) thymocytes did not generate cytolytic activity toward H-2 K or D alloantigen unless they were also stimulated by H-2 I or non-H-2 alloantigens, even though spleen cells generated brisk cytolytic activity toward H-2 K or D alone. Backstimulation by stimulating strain T lymphocytes accounted for neither the response of spleen cells toward H-2 K or D alloantigen nor the response of CR thymocytes to a full set of alloantigens. In addition, lack of non-T accessory cells did not account for the CR thymocyte pattern of reactivity. Rather, CR thymocytes appeared to be relatively deficient in helper T lymphocytes (HTL). CR thymocytes generated specific cytolytic activity toward H-2 D alloantigen when T cell growth factors (TCGF) or cloned alloreactive helper T lymphocytes were added to culture. CR thymocytes contained fewer HTL precursors detected at limit dilution than spleen cells did. Thus spleen cells generated cytolytic activity toward class I alloantigens alone, but under the same culture conditions CR thymocytes had to be stimulated by both class I and class II alloantigens. Class II alloantigens may be required to stimulate cytolytic activity only under culture conditions in which class I-reactive HTL are not sufficient to provide a minimal threshold of help.
D000818:Animals; D003348:Cortisone / Q000494:pharmacology*; D003602:Cytotoxicity, Immunologic; D005260:Female; D007519:Isoantigens; D007959:Lymphocyte Culture Test, Mixed; D051379:Mice; D008810:Mice, Inbred C57BL; D008811:Mice, Inbred DBA; D008937:Mitomycins / Q000494:pharmacology; D051381:Rats; D013154:Spleen / Q000276:immunology; D013601:T-Lymphocytes / Q000187:drug effects / Q000276:immunology*; D013950:Thymus Gland / Q000166:cytology
D007519:Isoantigens; D008937:Mitomycins; D003348:Cortisone