Studies on the Mechanism of Isoantigenic Variant Formation in Heterozygous Mouse Tumors. II. Behavior of H-2 Antigens D and K: Cytotoxic Tests on Mouse Lymphomas2

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Abstract
Two (A × A.SW)F1 hybrid mouse lymphomas were tested for transplantability to (A.SW × DBA)F1, (A.SW × C3H)F1, and A.SW mice. Tumors arising in these mice were tested for the presence of the H-2-determined isoantigens D and K, by the cytotoxic technique of Gorer and O'Gorman. Each of the 12 tumors which grew progressively in (A.SW × DBA)F1 mice had lost antigen K, while D was present in varying degrees in 11 of 12 tumors. Six of 6 takes in (A.SW × C3H)F1 mice had lost both antigens D and K. In three instances, the absence of D in a significant proportion of the cells in A.SW × DBA sublines could be correlated with transplantability to (A.SW × C3H)F1 and A.SW mice, where the cells lacking D were apparently selected for. The fact that antigen K can be lost alone or together with D, but D cannot be lost without K is tentatively attributed to somatic crossing over.