DEMONSTRATION OF A MURINE CELL-SURFACE COMPONENT WITH AFFINITY FOR EXOGENOUS BETA-2 MICROGLOBULIN

Murine and human β2‐microglobulin (β2m) bind to various types of mouse cells. The binding is saturable and displays a single association constant of about 1 × 109 liter/mol. The binding of β2m to splenocytes was not affected by a variety of metabolic inhibitors but was temperature‐dependent. It is suggested that the β2m “receptor” exhibits a temperature‐dependent conformational change since the “receptor”, whether integrated into the membrane or solubilized by the detergent Triton X‐100, binds β2m poorly at low temperatures. Spleen T and B lymphocytes display more binding sites than thymocytes, kidney, liver and brain cells. The relative amounts of the β2m‐binding “receptor” on these cell types are strongly correlated to the relative amounts of H‐2 antigens. This correlation is also obvious for the teratocarcinoma cell line F9, which lacks both β2m “receptor” and H‐2 antigens, but spermatozoa, which express very small amounts of H‐2 antigens, have an appreciable amount of the β2m “receptor”. The latter observation, together with the fact that alloantisera directed against H‐2 K and D antigens do not measurably affect the binding of β2m to the “receptor”, may argue against the notion that the β2m “receptor” represents H‐2 antigens which have lost their endogeneous β2m. Normal mouse serum contains a component which inhibits the binding of β2m to splenocytes. It is likely that this serum protein is identical to a newly discovered H‐2 antigen‐like glycoprotein. The β2m “receptor” appears to be under the control of the major histocompatibility complex as splenocytes of the H‐2f haplotype bind considerably more β2m than splenocytes of other haplotypes. Copyright © 1979 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim