Dysregulation of p56^lck Kinase in Patients with Systemic Lupus Erythematosus

Abstract

In this study we investigated one of the possible mechanisms of p56^lck down-regulation in peripheral blood lymphocytes (PBLs) from Systemic Lupus Erythematosus (SLE) patients and we correlated p56 dysregulation with accelerated apoptosis in SLE PBLs. PBLs from SLE patients and healthy donors were isolated. p56^lck protein expression and Ick mRNA level were estimated by immunoblotting and RT-PCR, respectively. FACS analysis was used to evaluate the apoptosis and p56 levels in apoptotic and non-apoptotic PBLs. A non-radioactive Tyrosine Kinase Assay Kit was used to measure p56, ^ck activity. Our results demonstrated that PBLs from SLE patients displayed lower levels of Ick mRNA and p56^lck protein as compared to healthy donors. The apoptosis of fresh or cultured PBLs was enhanced in SLE patients, especially in anti-DNA negative group. The expression of p56^lck was inverse correlated with apoptosis of fresh and cultured SLE PBLs, especially in anti-DNA negative patients. Double staining FACS analysis showed that p56^lck expression was lower in apoptotic than in non-apoptotic PBLs. p56^ick specific activity was directly correlated to apoptosis in SLE PBLs. While the low expression of p56^lck may be the result of lower degree of synthesis, the increased specific activity could directly correlated to the extent of apoptosis in SLE PBLs. Based on our observations, we assume that the p56^lck dysregulation could play a role in SLE pathogenesis

Key Words:

• SLE
• p56^lck
• apoptosis