Specific CD45 isoforms differentially regulate T cell receptor signaling.

Multiple isoforms of T cell CD45 tyrosine phosphatase are expressed as a result of alternative RNA splicing among extracellular exons. To discern the presence and identity of distinct functions among CD45 isoforms, we compared thymic T cell activation responses by elevating expression of two CD45 isoforms normally found on quiescent T cells. We report that CD45RABC significantly increased CD4+ thymic T cell proliferation in both a mixed …