Immunoperoxidase staining of early human melanoma colonies with monoclonal antibodies. A new method for in vitro antigenic-morphologic correlation.

The ability to evaluate antigenic expression within the clonogenic fraction of a tumor population has heretofore been limited by the need to grow large numbers of cells derived from clonogenic cells prior to immunoassay. This preliminary report describes the authors' initial experience with a simplified, efficient technique for analyzing antigenic expression among and within early colonies from a human solid tumor. Avidin-biotin immunoperoxidase staining of human melanoma colonies grown in semisolid medium yielded excellent cell retention, morphologic preservation, and antigenic localization. This method appears promising for antigenic-morphologic correlations among clonogenic tumor cells and may be useful for further studies of human tumor heterogeneity and differentiation.