Antibodies to Merkel cells in human sera. Incidence and significance

Antibodies to Merkel cells (MC) are not known to occur in human sera. Using a newly described technic, we looked for the presence of antibodies directed against skin structures in sera from 2,300 patients with various dermatologic and hematologic disorders, as well as graft-versus-host disease (GVHD). Three of these sera (0.1%) were found to react with MC. One monoclonal IgM antibody was present in serum obtained from a patient with chronic cold agglutinin disease, the second from a patient with GVHD, and the third from a patient with pemphigus vulgaris. The present inadequate knowledge about normal MC function and the absence of described symptoms of MC dysfunction preclude analysis of the pathogenic significance of these MC antibodies in human sera.