[An analysis of small differences between mice of lines C57BL/10 and 129 with regard to the chief system of tissue compatibility, H-2].

The differences in the H-2 system between mice of the C57BL/10 (H-2b) and 129 (H-2bc) were studied in crosses B10.D (H-2d) or recombinant strains R106 (KbSbDda), R107 (KbSbDd) and R101 (KdSdDb) with strains 129 or B10.129 (6M). Most skin grafts from the strain C57BL/10 were rapidly rejected in the F1 hybrids derived from the crosses with strains B10.D2, R106 and R107, thus indicating to the effect of the relatively strong H-locus either in the D region or in the Tla region of H-2b. Chronic responses were observed in the F1 hybrids derived from crosses with the strains R101 and R103, indicating to the weak effect of another locus. However all the skin grafts survived in the F1 hybrids with the strain HTG (KdSdDb). This weak H gene is apparently located to the left of the crossover in the recombinants R101 and R103, but to the right of the crossover in the HTG, i. e. between the loci Slp and H-2D. The new locus is tentatively designated as H-2W.