HLA-SB in the south of France. Correlation between locally derived and reference typing reagents

The HLA-D region of the Major Histocompatibility Complex has been subdivided since 1978 (Mawas et al. 1978) into two subregions separable by recombination: a telomeric subregion (closer to HLA-B), coding for the classical HLA-DR or Dw specificities (Mawas et al. 1980) as well as for the more recent MT series (Park et al. 1980); and a centromeric subregion (closer to GLO), coding for a new series of alleles provisionally named SB (for secondary B cell antigens) (Shaw et al. 1980, 1981a). Reagents allowing the identification of six independent alleles have been characterized in two laboratories (Charmot et al. 1980 and Shaw et al. 1980, 1981b) using the technology of primed lymphocytes typing (Sheehy et al. 1975; Mawas et al. 1975). The existence of this new locus is supported by the following arguments: population studies by Shaw demonstrating five traits distinct from DR behaving as alleles (Shaw et al. 1981b), analysis of two informative SB/DR recombinant families (Mawas et al. 1978; Mawas et al. 1980; Shaw et al. 1981a), and, finally, studies of mutants showing independent loss of DR expression without loss of SB expression (Kavathas et al. 1981). The present report summarizes the HLA-SB typing of 109 unrelated individuals from the South of France and segregation studies in 14 unrelated families; a first attempt to correlate local "SB" reagents with the NIH reference standards is presented.