In the 11th International Histocompatibility Workshop prescreening study, HLA Class I and Class II monoclonal antibodies (mAb) were tested on panels of peripheral T and B cells and homozygous typing cell (HTC) lymphoblastoid lines. The 102 Class I mAb, of which 64 were new, were screened on 63 HTC lines and 20 peripheral T cells. The 144 Class II mAb were tested on 63 HTC lines, 20 peripheral B and 10 peripheral T cells. For Class I, 45 pf the 102 mAbs tested proved to have clear and identifiable reaction patterns on both PBL and HTC lines and included several interesting new HLA-A and -C locus antibodies. Of the 144 Class II mAb, of which 99 were new, 18 DR, 22 DQ and 7 DP antibodies were judged excellent. The DR antibodies included some which were antigen-specific but the majority were complex antibodies, while the DQ antibodies, as previously, identified the majority of DQ antigens both singly and in combinations. The encouraging number of DP antibodies was interesting in the limited range of sites they appear to detect.
