Association of IgA nephropathy with T cell receptor constant alpha chain gene polymorptism

Abstract

T-cell receptor (TCR) proteins recognize a complex of an antigen-derived peptide bound to the cell surface products of the major histocompatibility complex (MHC) that could be of importance in the immunopathogenesis of IgA nephropathy (IgAN). Previous studies found no difference on TCR constant β chain gene frequencies in IgAN compared with control. Yet no study on the TCR α gene in IgAN was reported. We studied the TCR Cα gene polymorphisms by restriction fragment length polymorphism (RFLP) in 53 patients with IgAN and in comparison with 67 healthy controls. The patients were also classified into different histopathological grading (I, II, and III with increasing histological severity) and renal functions. The extracted DNA were digested with Taq I enzymes and probed with a full-length TCR-α cDNA clone p1.2α probe. A 7-kb C-α Taq 1 fragment is found in 32 of 53 patients (60.3%) compared with 26 of 67 controls (38.8%) (P < 0.05). There was no association of any polymorphic fragment, including the 7-kb fragment, with either the histological grading or renal function. It is concluded that the TCR C-α gene is associated with IgAN but not with the prognosis of the disease.