Hybridizations with gene-specific probes of variable region heavy chain (VH) immunoglogulin gene PCR-products from two synovial membranes (S1, S2) and peripheral venous blood (B) from a patient with rheumatoid arthritis undergoing synovectomy of two peripheral joints. Hybridizations were performed, on the same nylon membrane, using chemiluminescence end-labeling, with exposure on film for one hour. (a) Hybridization with a framework region (FR)-3 specific probe. Ladders of bands indicate a polyclonal repertoire of VH1, VH3 and VH4 genes. (b) After 'stripping' with boiling water, the membrane was hybridized to a probe specific to the VH1 gene, VH51P1. Hybridizations occurred with several VH1 genes that represent VH51P1. (c) Hybridization to a VI.9III (VH3)-specific probe. Hybridizations occurred with several VH3-genes that represent VI.9III.