Isolation of MUC1-primed B lymphocytes from tumour-draining lymph nodes byimmunomagnetic beads

The humoral immune response against a tumour-associated antigen, polymorphi c epithelial mucin (PEM, MUC1) in cancer patients was studied by isolating specific B cells primed for the antigen. Human B lymphocytes from tumour-dr aining lymph nodes, obtained from 13 patients with epithelial cancers, were immunoselected with magnetic beads coated with a 60mer synthetic peptide c orresponding to three tandem repeats of the protein core of the MUC1 antige n. Short-term cultures of B cells were established utilizing interleukin-10 (IL-10), IL-4 and monoclonal antibody anti-CD30, and were maintained for a maximum of 3 weeks. B cell culture supernatants contained human anti-MUC1 antibodies, as detected by enzyme-linked immunosorbent assay, in 6/12 of th e patients tested. Five of these patients, all with early-stage cancer, als o had high levels of circulating anti-MUC1 IgM antibodies in the serum. A s ignificant correlation was found (two-tailed P = 0.041) between the presenc e of circulating anti-MUC1 antibodies and the ability to isolate PEM-specif ic B cells from tumour-draining lymph nodes. The technique proposed provide s a useful method for the analysis of natural immunity against defined tumo ur antigens.