Alteration of a membrane associated marker in transplantable rat pancreatic acinar cell carcinoma

A monoclonal murine IgG has been developed which detects a cellular and intracytoplasmic membrane marker expressed only in the rat pancreatic acinar cell. Membrane aberrations in chemically induced transplantable rat pancreas acinar cell adenoma and carcinoma were examined using this IgG. The presence of this membrane marker was assessed by indirect immunofluorescence using paraffin sections of normal pancreas, acinar cell adenoma and transplanted tumors from rats and nude mice. The intracytoplasmic membrane of cells in acinar cell adenoma revealed a much higher intensity of fluorescence compared with normal acinar cells. In contrast there was an almost complete absence of fluorescent staining of the intracytoplasmic membranes of acinar cell carcinoma while their cell membranes showed an intensity of fluorescence far exceeding that of normal acinar cells. These findings suggest a defect in the dynamics of membrane-associated antigen(s) in these cancer cells.