A subpopulation of lymphocytes was detected using a novel assay utilising calf erythrocytes sensitised with the Facb fragment of rabbit immunoglobulin G (IgG). This subpopulation was detected in raised percentage numbers in the peripheral blood of rheumatoid patients and was also present in rheumatoid synovial fluid. A cross-sectional study showed that these increased numbers did not map disease activity and were not related to the expression of HLA-DR4. Although normal percentage numbers were present in the peripheral blood of patients with osteoarthritis and ankylosing spondylitis, the elevation is not specific to rheumatoid arthritis since occasionally healthy volunteers showed raised percentages, and percentage numbers also increased transiently following skin testing of sensitised individuals and during viral infection. The receptor for Facb sensitised erythrocytes (Facb receptor) appears to be a high avidity Fc receptor which is specific for the CH2 region of IgG and is trypsin and neuraminidase resistant. Phospholipase C also did not diminish Facb receptor expression. The Facb receptor was detected on a small percentage of polymorphonuclear leucocytes and monocytes as well as on lymphocyte surfaces. Lymphocytes bearing Facb receptors displayed neither T nor B cell markers using conventional techniques. Functional assays showed these cells to be noncytotoxic. A possible role for these cells in immunoregulation is discussed.
|Date of Award||1982|