Lymphokine regulation of surface Ia expression on rat B cells.
Class II major histocompatibility antigens (Ia) play a major role in regulating T-B cell interactions; therefore, regulation of the amount of Ia on B cells may be an important point of control in the immune response. Mitogens in human and murine systems have been reported to increase Ia expression on B cells, and in the mouse the lymphokine BSF-1 (IL-4) markedly enhances Ia expression. This report describes studies of lymphokine and mitogen regulation of class II expression on rat B cells. Mitogens known to activate resting B cells, such as DxS/LPS, anti-IgM, STM, and Con A, induced increases in Ia expression. Highly purified murine IL-4 was found to have no Ia-enhancing activity on rat B cells, although the same preparation increased Ia expression eightfold on murine B cells. This confirms other recent reports that IL-4 is a species-specific lymphokine and will not cross even narrow phylogenetic barriers. Rat B cells were not refractory to lymphokine-induced enhancement of Ia expression, since lymphokine(s) contained in a Con A-induced supernatant enhanced Ia expression. Furthermore, murine IL-5-containing B151-CFS was able to markedly increase Ia expression on resting rat and mouse B cells. This activity was not lost after heat inactivation of B151-TRF2, indicating that B151-TRF1 (IL-5-like activity) was probably responsible for the increase in Ia expression. These results suggest Ia expression on rat B cells, like human and murine B cells, is an early activation event which is regulated by signals which act on resting B cells. Furthermore, while IL-4 is important in Ia regulation, it is not the only lymphokine involved, since the IL-4-free, B151-K12 supernatant was able to enhance Ia expression on resting rat and mouse B cells.
Leitenberg
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Department of Microbiology, University of Iowa, Iowa City.
Feldbush
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D000818:Animals; D000911:Antibodies, Monoclonal; D001402:B-Lymphocytes / Q000276:immunology*; D005434:Flow Cytometry; D000949:Histocompatibility Antigens Class II / Q000276:immunology*; D015847:Interleukin-4; D015848:Interleukin-5; D007378:Interleukins / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects; D008222:Lymphokines / Q000494:pharmacology*; D051379:Mice; D051381:Rats; D013045:Species Specificity
D000911:Antibodies, Monoclonal; D000949:Histocompatibility Antigens Class II; D015848:Interleukin-5; D007378:Interleukins; D008222:Lymphokines; D015847:Interleukin-4