Reactivity of Anti‐HLA Sera against Mouse Lymphocytes*

Abstract

The reactivity of anti-HL-A hyper-immune sera was tested by the microlymphocytotoxicity technique (LCT) against a panel of mouse lymphocytes. Three levels of reactivity were observed: negative (immune sera titer 1:20 or less), weak (titer 1:40-1:80, with the percentage of dead cells less than 50%) or strong (titer 1:60 or more with 100% killing). Thirteen normal human sera were non-reactive. Of 60 hyper-immune sera, 11 were strongly reactive. Tests using congenic lines showed that the reactivity was controlled at the H-2 complex. One serum (CODRON) was studied in detail. When tested against a panel of strains carrying 10 different H-2 haplotypes, it reacted strongly against lymphocytes H-2d, ja, k, p and r; and did not react, or at least only weakly, against lymphocytes H-2b, f, q, s and v. Tests using mouse strains carrying the recombinant H-2 haplotypes b4, i5, i, y2, g, g2 and t1, suggested that the observed reactivity was directed against structures controlled at the K end of the H-2 complex (H-2.47?). Absorption-elution experiments with human and murine lymphocytes and platelets confirmed that the structures recognized by serum CODRON were determined at the major histocompatibility complex.