Murine
monoclonal antibodies (MAbs) were produced with reactivity to human
malignant melanoma. Six MAbs, 3 of the IgGI (LS113, LS140, LS152) and 3 of the
IgG2a (LS59, LS62, LS76) subclasses, were selected for their binding, with an identical pattern of reactivity, to a novel
melanoma-associated
antigen. As characterized by the
enzyme-linked
immunosorbent assay (ELISA), these MAbs were found to be positive on
n-octyl-beta-D-glucopyranoside extracts of all 10
melanoma cell lines tested and on extracts of 22 metastatic
melanoma tumors. The
antibodies had minimal reaction with a panel of 14 normal adult
tissue extracts. A degree of cross-reactivity was observed with 50% of 39 non-
melanoma tumor extracts. The results obtained with the ELISA on cell line and
tissue extracts were duplicated using the ABC method of
peroxidase staining. The pattern of cross-reactivity, as demonstrated by the intense staining of
paraffin-embedded and frozen tissue sections of normal, benign and malignant tissues, defines the recognized
protein as a neuroglandular
antigen (NGA).
Immunoadsorbents made with the
antibodies were used to purify the
antigen shed from cultured
melanomas. All 6 MAbs recognized this purified
antigen while 5 other antimelanoma
antibodies did not react with it. On gel electrophoresis this
antigen is a highly glycosylated
glycoprotein with a
protein core of 21 kDa.