ASSOCIATION OF IGA NEPHROPATHY WITH T-CELL RECEPTOR CONSTANT ALPHA-CHAIN GENE POLYMORPHISM

T-cell receptor (TCR) proteins recognize a complex of an antigen-deriv ed peptide bound to the cell surface products of the major histocompat ibility complex (MHC) that could be of importance in the immunopathoge nesis of IgA nephropathy (IgAN). Previous studies found no difference on TCR constant beta chain gene frequencies in IgAN compared with cont rol. Yet no study on the TCR alpha gene in IgAN was reported. We studi ed the TCR C alpha gene polymorphisms by restriction fragment length p olymorphism (RFLP) in 53 patients with IgAN and in comparison with 67 healthy controls. The patients were also classified into different his topathological grading (I, II, and III with increasing histological se verity) and renal functions. The extracted DNA were digested with Taq I enzymes and probed with a full-length TCR-alpha cDNA clone p1.2 alph a probe. A 7-kb C-alpha Taq I fragment is found in 32 of 53 patients ( 60.3%) compared with 26 of 67 controls (38.8%) (P < 0.05). There was n o association of any polymorphic fragment, including the 7-kb fragment , with either the histological grading or renal function. It is conclu ded that the TCR C-alpha gene is associated with IgAN but not with the prognosis of the disease. (C) 1997 by the National Kidney Foundation, Inc.