Role of CD59 in T cell activation induced by non-lethal complement attack

Objective: To study the mechanism of T-cell activation induced by non-lethal complement attack and the role of CD59 in this process. Methods: Human CD59 and its transmentbrane counterpart CD59TM cDNA were transfected into murine thymoma EL-4 cells. Activation and proliferation of EL-4 transfectants were observed with MIT assay. Results: Both CD59 and CD59 TM cDNA expressed on EL-4 cells effectively inhibited complement-mediated membrane damage. Cross-linking of CD59 with antibody induced activation of CD59/EL-4 cells but not CDS9TM/EL-4 cells. This effect was inhibited by Herbimycin A. a special protein tyrosine kinase (PTK) inhibitor. Non-lethal complement attack induced CD59/EL-4 but not CD59TMIEL-4 cell to proliferate, and this reaction was not blocked by Herbimycin A. Conclusion: CD59 takes part in T cell activation induced by non-lethal complement attack. The mechanisms of T cell activation induced by non-lethal complement attack arc different from those by cross-linking of CD59.