Beta 2-microglobulin: association with lymphocyte receptors.

beta(2)-Microglobulin (beta(2)m) is a low-molecular-weight protein constituent of lymphocyte membranes. Amino acid sequence analysis has revealed a high degree of homology between the beta(2)m and certain regions of immunoglobulin molecules, suggesting a possible recognition function for the beta(2)m, in analogy with the immunoglobulins. The data presented demonstrate that highly specific antiserum against beta(2)m blocks lymphocyte reactivity against allogeneic cells in mixed leukcocyte cultures and against phytohemagglutinin, both of which processes presumably function via a cell surface receptor on thymus-derived (T) lymphocytes. There is very little inhibition of T lymphocyte rosette formation with sheep red blood cells. The findings suggest a possible relation between the beta(2)m and recognition units on the T lymphocyte surface.