Changes of costimulatory signals in aplastic anemia patients

Objective: To explore the role of costimulating system in the pathogenesis of aplastic anemia(AA). Methods: The expression of costimulatory molecule CD28 in T cells and the expressions of the CD28 ligands of CD80 and CD86 in B lymphocytes in AA patients were determined by flow cytometry. Meanwhile, the mononuclear cells of severe aplastic anemia(SAA) patients were cultured in vitro for 12 hours to investigate the changes of CD28 in T cells before and after culture. Results: In SAA patients,the proportions of CD4+/CD28+ T lymphocytes and CD8+/CD28- T lymphocytes were higher than that in normal. After immunsuppression therapy, the proportion of CD8+/CD28- was decreased. In chronic aplastic anemia(CAA) patients,the proportion of CD4+/CD28- T cells was higher than that in the control. The expression rate of CD8+/CD28- was higher than those in the control and SAA patients. After culture in vitro, the proportion of CD8+/CD28- T cells was significantly decreased. Conclusion: The changes of costimulatory molecular CD28 in T cells result in high expressions of some subtypes of T cells, which have a relationship with the pathogenesis of AA.