VH3-21 B-CELLS ESCAPE FROM A STATE OF TOLERANCE IN RHEUMATOID-ARTHRITIS AND SECRETE RHEUMATOID-FACTOR

Background: Rheumatoid factor (RF) is a characteristic but not pathognomic feature in patients with rheumatoid arthritis (RA). It is unknown whether the repertoire of immunoglobulin genes utilized by RF(+) B cells of RA patients is unique and whether RF(+) B cells in normal individuals are silenced or deleted. Materials and Methods: Clonal B cell populations were established from the peripheral blood of normal donors (127 B cell clones), RA patients (113 RF(-) and 60 RF(+) B cell clones) and patients with primary Sjogren's syndrome (82 RF(-) and 47 RF(+) B cell clones) by coculturing with anti-CD3-stimulated T helper cell clones. The cross-reactivity pattern of antibodies secreted by the B cell clones was determined by ELISA on a panel of antigens. The molecular structure of the IgM heavy chains was characterized by VH family-specific RT-PCR and sequencing. VH elements which correlated with RF specificity were identified. The responsiveness of B cells expressing these VH elements to T helper cell signals was compared in normal individuals and RA patients. Results: The majority of RF(+) B cells were monospecific when specificity was tested on five antigens. RF(+) B cells expressed a significantly different repertoire of VH gene segments than RF(-) B cells. In particular, the VH3 gene segment V3-21 was not detected in B cell clones from normals but was the most frequent VPI element in RF(+) B cell clones from RA patients. Most of the V3-21 sequences were in germline configuration. The correlation between RF specificity and V3-21 gene segment usage was maintained in patients with Sjogren's syndrome. V3-21 transcripts were present in peripheral blood R cells from normal individuals. VH3-21(+) B cells from RA patients but not from normal donors wore responsive to preactivated T helper cells. Stimulation with a bacterial superantigen could overcome the nonresponsiveness of V3-21(+) B cells in normal donors anti induce the secretion of RF. Conclusions: RF production is correlated with the usage of the V3-21 gene segment in two distinct RF(+) diseases. in patients with these diseases, V3-21(+) B cells secrete antibodies with RF activity in response to activated T helper cells. V3-21(+) B cells remain in a state of nonresponsiveness in normal individuals that can be broken by superantigen stimulation. The germline configuration of VH3-21(+) RF(+) immunoglobulins in RA patients suggests that the loss of tolerance is not an antigen-driven process.