Relationship between β2-Microglobulin and Cell-Surface Alloantigens of the Mouse

Molecular relationships between β2m and other cell surface antigens (H-2, Tla, Ia, and Thy-1) were studied with the double immunofluorescence method. Cells were incubated with an antiserum against one antigen, capped, and then tested with an antiserum against a second antigen. Capping of β2m on thymocytes led to simultaneous capping of H-2 and Tla but not Thy-1 antigens; capping of H-2 and Tla (but not Thy-1) antigens resulted in capping of all β2m detectable by the immunofluorescence method. Similarly, capping of β2m on B or T lymphocytes resulted in capping of H-2 and vice versa. Ia antigens on B lymphocytes were not capped after the redistribution of β2m. We conclude from these data that, in the cell membrane of thymocytes, virtually all the β2m molecules are associated with H-2 and Tla, but not with Thy-1, and that on the cell surface of T or B lymphocytes, virtually all β2m is associated with H-2 but not with Ia. We found no evidence of any significant free β2m on either thymocytes or splenocytes.