Demonstration of two distinct forms of released low‐affinity type interleukin 2 receptors

摘要

AbstractThe release of interleukin 2 (IL2)‐binding proteins, derived from the 55‐kDa low‐affinity IL2 receptor (IL2R; L chain), has been observed for virtually all L chain‐bearing cells in either humans, the mouse or the rat. Based on the characterization of the released human L chain as a molecule 10 kDa smaller than the cell surface receptor, either proteolytic cleavage or differential splicing of the L chain‐encoding mRNA have been suggested as mechanisms underlying the receptor release. Combining affinity labeling of the L chain withl25I‐labeled IL 2 and immunoprecipitation with L chain‐specific monoclonal antibodies applied for the detection of soluble mouse IL 2R revealed the existence of two classes of soluble receptors, one being of the same size as cell surface expressed L chain, the other of 45‐kDa apparnent molecular mass. These findings raise the possibility of mechanisms of receptor release other than those discussed fo