Identification of human acinar cell carcinoma by monoclonal antibody and in vitro differentiation.

Methylnitrosourea (MNU)-induced carcinomas in organ-cultured human pancreas when injected into nude mice produced subcutaneous carcinomas none of which recognizable as being of acinar cell origin. Both monoclonal antibody to acinar cell surface marker produced by hybridoma, and in vitro tumor cell differentiation were used to detect tumors of acinar cell origin. Only 1 out of 14 tumors, a highly undifferentiated carcinoma, proved to be of acinar origin. This tumor was composed of cells devoid of zymogen granules but with abundant acinar cell surface marker. The acinar origin of this tumor was also confirmed by its differentiative features after 7 weeks of culture.