The Lymphocyte Surface

Abstract

Differences in the electrokinetic properties of thymocytes from A.CA (H-2^f) and A.SW (H-2^S) mice were observed, the anodic electrophoretic mobility (EPM) of H-2^S cells being (9–14%) higher than that of H-2^f cells. The age, sex of the animals and the proportion of hydrocortisone-resistant cells in the thymus did not appear to have any influence on this observation. Studies on thymocytes from F1 hybrid and backcross mice provided the convincing evidence that the differences in the EPMs of H-2^f and H-2^S cells are under genetic control. The EPM of H-2^f/H-2^s heterozygous cells was similar to the EPM of homozygous H-2^f cells. The differences in the EPMs of the H-2^f and H-2^S thymocytes depend upon the striking differences in their surface topochemistry. Compared to the H-2^S thymocyte cell periphery, the H-2^f cells have a substantially higher number (330%) of cationogenic amino groups but only a smaller number (30%) of anionogenic groups (α-carboxyl groups of N-acetylneuraminic acid and phosphate groups susceptible to alkaline phosphatase). The presence of SH groups on the surface of both H-2^f and H-2^S thymocytes was not detectable. It is suggested that the difference in the cell surface topochemistry of thymocytes from the mice investigated is perhaps related to different amounts and/or types of surface membrane molecules under the control of the major histocompatibility complex.