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The accumulated data in the cell line panel made it possible to examine the associations between alleles at widely separated loci within the MHC. The calculation of 2- or 3-point delta values was clearly inappropriate given the limited size and the selection of the panel. Rather, we could determine whether particular “supratypes” or “extended haplotypes” could “split” apparently homogeneous alleles at multiple loci.

DO beta/MspI blots were received from two laboratories. Fragments well identified on at least one lab’s blots were included as standard fragments.

The purpose of the Workshop studies of restriction fragment length polymorphisms in class III genes was to correlate specific bands with alleles of C2, BF, C4A, C4B, 210HA, and 210HB. At the time of the Workshop, there were few protein typings available for the Workshop core cells. It was, therefore, decided to guess at complotypes (BF, C2, C4A, and C4B allelic sets occurring in populations and inherited in families as single genetic units) in those panel cells carrying HLA-B and DR specificities known to mark extended haplotypes (1) or supratypes (2). After the Workshop, complement typings became available for 51 core cells (Table 1). The complotype guesses for 14 of the 23 cells with probable extended haplotypes were confirmed in all but one instance. One cell (9027) was guessed to be homozygous SC30 (BFS, C2C, C4A3, C4BQ0), but was in fact heterozygous SC30/SC31. Two other individuals carrying probable nonextended haplotypes were probably heterozygous: C4A5, C4A6 (9095), and BFF, BFS (9080). All cells for which RFLP analyses were performed and for which complement types were available or guessed were used for correlation analyses.

During the Tenth Workshop, 27 anti-sera in the Antigen Society and 22 anti-sera in the Core serology serum set were provided for the serologic analysis of the supertypic HLA-B locus specificities Bw4 and Bw6. The serum sets included 12 monoclonal antibodies with Bw4 or Bw6 specificity. For each of the submitted sera, Q score, R values, % extra, and missed reactions, as well as “tail” antigens derived by 2x2 comparison of their reactivity on Caucasians, Negroes, and Orientals, are shown in Tables 1 and 2.

DRbeta/MspI blots were received from four laboratories. In spite of the standardized technique, the overall intensity of the blots and the number of fragments detected were somewhat variable. Marker bands were remeasured where necessary and the data were pooled as follows: 1. Faint bands were listed as standard fragments when they were identified by at least two of the four laboratories. 2. Faint bands seen by only one laboratory, sometimes in only one lane, were not included. This was seen most often with bands of high kb and may have been due to incomplete digestion. 3. Discrepancies between blots were resolved in favor of the majority, or in favor of the positive identification when two labs recorded a band and two did not. 4. Faint bands in particular were sometimes resolved as a doublet in one lab’s blots, but appeared as a singlet in others. Such bands were considered as two standard fragments when they could be consistently resolved on the blots from at least two labs; otherwise they were considered as one band. 5. Because of small differences in measurement from blot to blot and from lab to lab, the standardized molecular sizes of cross-hybridizing bands were not always exactly the same. In addition, the pattern of positives and negatives of the same band with different cross-hybridizing probes was not always identical. Therefore, cross-hybridizing bands were identified by overlaying the pairs of autoradiographs of blots hybridized with the relevant probes.