CD45 ISOFORMS ON HUMAN CD4(+) T-CELL SUBSETS

We have examined the level of surface expression and functional proper ties of leukocyte function associated antigen-1, very late antigen-4, and CD45 isoforms on a panel of human CD4(+) T-cell clones representat ive of TH0, TH1, and TH2 cells. There were no qualitative differences in the expression of these antigens among the three types of CD4(+) T- cell clones. However, CD45RB was the only CD45 isoform that provided a costimulatory signal in a solid-phase antibody-induced cellular proli feration assay. Additionally, the antigen-induced proliferative respon se of T-cell clones was inhibited by soluble anti-CD45RO and anti-CD45 RB antibodies. Our results suggest that CD45 informs differentially pr ovide costimulatory signals to T cells. However, the ability of each C D45 isoforms to provide a costimulatory signal does not differ among t he Th-0, TH1, or TH2 T-cell populations.