Individual recognition gene complex

Several lines of evidence indicate that MHC class and allotype restriction is due to thymic selection of alfi complexes [52], Thus, in most cases neither the a chain alone nor the P chain (nor any Va or gene segment) is individually sufficient for the recognition of MHC class ([32,53-55] one exception is discussed in [56]) and allotype [35,57-59], However, individual a and p chains may recognize MHC molecules non-specifically, i.e. independently of class and type. Thus, the same a chain is shared by a/p TcR s specific for (1) pigeon cytochrome c and MHC class II Ek or Ek,b [37,58] (2) ovalbumin and MHC class II Ab [59] (3) an allotypic MHC class I Db [59],... 

Since the three a/p TcR s listed have been generated by in vitro manipulations (i.e. they have not been selected as a complex in the thymus) and do not cross-react, this particular a chain may impose a bias towards MHC recognition that is independent of class and allotype [59], Whilst this bias may also be due to selection of individual chains in the thymus, V and/or gene segments are clearly not individually selected [53,55]. 

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