Increase of IgA specific helper T alpha cells in patients with IgA nephropathy.

Patients with IgA nephropathy show an emergence of IgA dominant circulating immune complexes (CIC) as well as increased levels of serum IgA and/or IgA bearing peripheral blood lymphocytes. In order to elucidate immunological aberrations responsible for the increased IgA synthesis in such patients, quantitative and qualitative analysis was performed on T alpha cells which have been recently identified as possessing IgA specific helper activity on human B cells. Three different methods were employed to quantitate T alpha cells. These methods included a rosette formation of T cells with either bovine red cells coated with the IgA fraction of anti-bovine red cell antiserum or those coated with TNP and anti-TNP IgA antibody, and an analysis of T cells combined with fluorescein conjugated human IgA myeloma protein. T alpha cells were sorted by a fluorescence activated cell sorter and co-cultured with a B cell rich fraction to evaluate whether there is a qualitative difference in IgA specific helper activity between patients and healthy adults. T alpha cells were significantly increased in patients with IgA nephropathy while there were no significant changes in patients with chronic proliferative glomerulonephritis without mesangial deposition of IgA. There was no qualitative difference in IgA specific helper activity of T alpha cells between patients and healthy adults. It is suggested that increased levels of T alpha cells in patients with IgA nephropathy may be responsible for increased synthesis of IgA in such patients.