Typing for MLC determinants: methods and applications.

MLC typing of random individuals can be performed using a panel of inactivated HLA-D homozygous cells. Eight different HLA-D specificities are now internationally accepted. The evaluation of the results must take into account both the general responding capacity of the cell to be typed and the general stimulating capacity of the typing cells. An evaluation based on the 75th percentile is discussed in detail and some pitfalls are mentioned. Furthermore a description is given of primed lymphocyte typing (PLT), where cells primed in ordinary MLC cultures to one HLA-D determinant have the ability to respond in an accelerated way to similar HLA-D antigens when re-exposed to such cells in secondary cultures. In our experiments, an excellent correlation is found between these two ways of MLC typing provided that the cells used for priming are well characterized (i.e. HLA-D homozygous cells). Finally, some clinical applications of MLC typing are described, especially in connection with transplantation and association between HLA and various diseases.