Tissue distribution of antigen(s) defined by monoclonal antibody D8/17 reacting with B lymphocytes of patients with rheumatic heart disease.

Monoclonal antibody D8/17 originally prepared by immunization of mice with B cells from a patient with rheumatic heart disease (RHD) reacts with epitopes expressed on significantly elevated proportions of B cells (10-35%) from all patients with acute rheumatic fever or rheumatic heart disease. This B cell marker does not segregate with any known HLA or DR phenotype. We have examined the reactivity of D8/17 with a broad assortment of human tissues, using indirect immunofluorescence. Strong positive reactivity of D8/17 was observed with cardiac muscle, skeletal muscle, and smooth muscle of blood vessels. Positive fluorescent staining was also noted in cell membranes of hepatocytes and cells lining bile canaliculi as well as in epithelial cells of skin, esophagus, and cervix. D8/17 mAb binding to cardiac muscle was markedly diminished by preincubation of mAb with KH B cell line originally established from an RHD patient. D8/17 mAb binding to human heart was also inhibited by preincubation with myosin and tropomyosin but not by actin. Using the D8/17 mAb in immunoblots, positive binding was noted by the antibody to recombinant type M6 protein, vimentin, and myosin. Our findings indicate that the B cell antigen reacting with mAb D8/17 may be related to contractile proteins present in heart, skeletal and smooth muscle, and may also share epitopes with some components of group A streptococci.