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SELF RECOGNITION IN ALLOGENEIC THYMIC CHIMERAS. Self Recognition by T Helper Cells from Thymus-engrafted Nude ... Thymus Transplantation.
Brief Definitive Report





Self R e c o g n i t i o n b y T H e l p e r Cells f r o m T h y m u s - e n g r a f t e d N u d e M i c e is R e s t r i c t e d to the T h y m i c H - 2 H a p l o t y p e By ALFRED SINGER, KAREN S. HATHCOCK, AND RICHARD J. HODES

From the Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20205 Most T cells recognize conventional antigens only in the context of self determinants encoded within the major histocompatibility complex (MHC). Recently, it was shown (1) that the M H C determinants that T helper (Tn) cells recognize as self structures for responses to conventional antigens were entirely determined by the host environment in which the TH cells had differentiated, even if the host differentiation environment was fully allogeneic to the T n cells themselves. Thus, strain A T n cells from A ~ B fully allogeneic radiation bone marrow chimeras recognized conventional antigens in the context of host type strain B M H C determinants but did not recognize conventional antigens in the context of syngeneic donor type strain A M H C determinants. The present study was undertaken to evaluate the possibility that the thymus was the specific host element responsible for the restricted self-recognition repertoire expressed by TH cells. The T n cell populations examined in this study were obtained from the spleens of congenitally athymic nude mice that had been engrafted with neonatal thymic lobes that were allogeneic to the nude host. The self-specificity of these TH cells was determined by their ability to cooperate with either syngeneic (nude host type) or allogeneic (thymus type) B+ accessory cell populations for responses to either trinitrophenyl keyhole limpet hemocyanin ( T N P - K L H ) or to sheep erythrocytes (SRBC). To avoid alterations in the T n cell repertoire of thymic chimeras induced by in vivo priming to antigen in association with the presenting cells resident in these animals, all the cell populations used in this study were from unprimed animals. Materials and Methods Animals. Pregnant C57BL/6 (B6), A/J, and C3H/HeJ mice as well as normal adult B10, B10.A, B10.D2, B10.BR, and (B6 × DBA/2)FI (B6D2F1) mice were obtained from The Jackson Laboratory, Bar Harbor, Maine. BALB/c nu/nu mice were obtained from Charles River Breeding Laboratories, Wilmington, Mass. Antigens. TNP-KLH was prepared as previously described (2). SRBC were obtained from a single sheep, 1245, National Institutes of Health Animal Center, Poolesville, Md. Thymus Transplantation. Three thymic lobes from neonatal mice