Analysis of primary HLA-specific cytotoxic T cell response in graft-draining lymph nodes--a transgenic mouse model for in vivo recognition of human MHC antigens.

In order to characterize primary anti-HLA cytotoxic T cells and especially those involved in graft rejection, we have utilized a transgenic mouse model. Mice (non-transgenic and HLA-transgenic) were grafted with spleen cells originating from H-2-matched transgenic mice expressing HLA-B27 molecules, and cells from graft-draining lymph nodes were tested in CML assay to investigate the primary in vivo induced CTL responses. The results showed that HLA-B27 molecules were able to raise strong primary xenogeneic CTL responses. Results from split-well analysis indicated that although recognition of HLA-B27 by primary CTL induced in nontransgenic recipients is predominantly unrestricted by H-2, a small fraction (ranging from 2% to 27%) of the primary in vivo induced CTL is able to recognize HLA-B27 in an H-2-restricted manner. HLA-specific H-2-restricted CTL had never so far been demonstrated in the primary T cell response. Thus the protocol used in our study for the generation of a primary CTL response seems to provide not only a more appropriate representation of cytotoxic T cells sensitized by a graft, but also to be a more sensitive approach than the usually used in vitro mixed lymphocyte culture.