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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: BACKGROUND, METHODS, RESULTS. Meshes: Acute Disease, Animals, Cell Division, Graft Rejection, Histocompatibility Antigens Class II, Hypersensitivity, Delayed, Interferon-gamma, Lymphocyte Culture Test, Mixed, Major Histocompatibility Complex, Male, Mice, Mice, Inbred BALB C, Mice, Inbred C57BL, Mice, Knockout, Mitomycins, Skin Transplantation, Spleen, T-Lymphocytes, Cytotoxic.
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Is interferon-gamma necessary for initiating the acute rejection of major histocompatibility complex class II-disparate skin allografts? Context: Although interferon (IFN)gamma has immunostimulatory functions, it is not essential for the acute rejection of fully allogeneic grafts in mice. It is not known whether IFNgamma plays a critical role in the acute rejection of MHC class I- or MHC class II-disparate allografts. We studied the survival of skin allografts transplanted from fully allogeneic (BALB/c), MHC class I-disparate (bml), or MHC class II-disparate (bm12) donors to C57BL/6 wild-type (IFNgamma+/+) and IFNgamma gene-knockout (IFNgamma-/-) recipients. We also investigated the in vitro responses of IFNgamma+/+ and IFNgamma-/- T cells to MHC class II-disparate splenocytes. We found that IFNgamma-/- recipients reject BALB/c and bml skin grafts at the same rate as IFNgamma+/+ mice but are not capable of rejecting bm12 skin. Despite the inability of IFNgamma-/- mice to reject bm12 skin grafts, IFNgamma-/- T cells displayed vigorous proliferation and cytotoxic responses when stimulated with bm12 splenocytes in vitro. Furthermore, priming IFNgamma-/- recipients with bm12 splenocytes enabled these mice to reject bm12 skin grafts at a normal rate and to mount a cutaneous delayed-type hypersensitivity response to the bm12 antigen.
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The data demonstrate that IFNgamma is not necessary for generating effector mechanisms associated with acute transplant rejection but that it is required for initiating alloimmune responses to MHC class II-disparate skin grafts. Final Decision: yes