Unusual glucose phosphate isomerase isozyme patterns in lymphocytes from two C57BL/6J ↔ A/J allophenic mice

Analysis of C57BL/6J ↔ A/J allophenic mice for their lymphocyte composition, using H‐2 antigens as external markers, and glucose phosphate isomerase (GPI) isozymes as internal markers, has led to the discovery of two unusual mice. Both mice showed heterodimers of GPI isozymes upon electrophoresis of the lymphocyte lysate. Specific anti‐H‐2 antisera confirmed that the cells of the mice were of C57BL/6J and A/J origin, as expected, but that the “A/J” cells seemed to behave as F₁ hybrids containing the Gpi‐1^a and Gpi‐1^b alleles. Possible origins of the Gpi‐1^b allele in the “A/J” cells are discussed.