Increased utilization of the VH6 gene family in patients with autoimmune idiopathic thrombocytopenic purpura

The VH gene family utilization pattern among pokeweed mitogen-stimulated im munocompetent B cells (available repertoire) and naturally activated B cell s (actual repertoire) from the spleen was analysed in a group of patients w ith autoimmune idiopathic thrombocytopenic purpura (AITP). For this purpose a non-radioactive RNA in situ hybridization technique was employed, allowi ng detection of VH gene family expression in single cells. The results show that the VH gene family expression pattern in patients with AITP does not correlate with genomic complexity of the VH genes. Furthermore, the pattern of VH gene family utilization in AITP patients is statistically different from that of healthy controls in the available, but not in the actual reper toire. The VH5 gene family is used at a frequency of 11.3% in patients' res ting B lymphocytes, compared to 23.9% in controls. The VH6 gene family is u sed more frequently in patients (23.0% compared to 3.8% in controls). The i ncrease in VH6 gene expression is not reflected in the actual repertoire, w here the frequency of expression is 6.4%, and can therefore not be directly related to the presence of disease specific autoantibodies. (C) 1999 Acade mic Press.