Search

The analysis of 182 selected anti-B cell sera on 102 cells allowed us to identifysseveral clusters of sera. They showed no correlation with HLA-A, B or C specificities but many associations with the HLA-D determinants. In 10 families, most of these sera segregated with HLA, and five recombinants showed a linkage with the BD or D end part of the MHC. The panel distribution and the family analysis indicated that at least one (the Ly-Li system) and probably two segregant series could exist close to the HLA-D locus.

The existing estimates of the recombination fraction between DR and DP are quite variable and often based on anecdotal observations. We have estimated the DR/DP crossover frequency on the basis of families typed for HLA markers and GLD. The frequency of DR/GLO crossing over was 8.7% (23/264 informative meioses), maternal recombinations being about twice as frequent as paternal ones. Of 17 DR/GLO recombinant families typed for DPwl-6, DP was informative in 11 (13 recombinations) but only one of these gave rise to a DR/DP crossover. According to these data the DR/DP recombination fraction is below I%, in contrast to some earlier published materials. HLA-DR/DP haplotypic associations on 127 informative Caucasoid haplotypes have been evaluated. In agreement with previous studies, DR3 was positively associated with DPwl and, in addition, DR7 was found to be positively associated with DP-blank (not DPwl-6). The rare DPw6 allele is possibly associated with the DR4, Dw14 allele. The DR-DP haplotype profiles suggest other associations which might become significant if larger materials are tested. The frequency of DP alleles in a random material (N = 201) was found to be in accordance with most of the previously published frequences on European Cauca-soids with DPw4 as the predominating frequency (gene frequency 40%) and a blank frequency of 21%.

The Basques were previously shown to present a high frequency of HLA-B18 and BfF1, which are known to be associated with insulin dependent diabetes mellitus (IDDM). During the VIII International Histocompatibility Workshop, we studied HLA-A, B, C, DR; Bf, C4 and GLO.I polymorphisms in 51 unrelated French Basque IDDM patients and in 50 controls. Haplotypes were established by family studies in all controls and some patients. Two haplotypes were frequently found in the controls: HLA-A1, Bw57, BfS, C4 F1S, DR7 and HLA-Aw30, Cw5, B18, Bf F1, C4Fs degree, DR3. The first one was not found in the patients. All the components of the second haplotype had increased frequencies possibly as a consequence of linkage disequilibrium with HLA-DR3: a highly significant association between IDDM and HLA-DR3 was observed (90.2% vs 24.0%, relative risk (RR) = 29.1, P less than 10(-11)). The HLA-DR4 frequency was slightly increased (37.3% vs 16.0%), and HLA-DR2 was not found. The silent allele C4s degree was particularly associated with early diagnosed IDDM (86.7% in patients with age at onset under 20 years vs 57.1% in other patients, P less than 0.02). The high relative risk for HLA-DR3/DR4 heterozygous vs that of individuals, possibly HLA-DR3 homozygous, supported the hypothesis that two HLA-DR linked genetic factors could be involved in the inheritance of IDDM susceptibility.

We report the study of a serum from a polytransfused patient, that contains an anti-HL-A8 antibody reacting by the platelet complement fixation microtechnique. The specificity is confirmed by a study on a panel of 112 different platelets and by experiments of absorption-elution on platelets, lymphocytes and granulocytes.