Isolation and characterization of the canine melanoma antigen recognized by the murine monoclonal antibody IBF9 and its distribution in cultured canine melanoma cell lines.

OBJECTIVE

To characterize the canine melanoma antigen recognized by the murine monoclonal antibody IBF9 as to its cellular location, molecular size, protein and glycogen contents, and distribution in cell lines.

SAMPLE POPULATION

7 cultured canine melanoma cell lines.

PROCEDURE

Molecular characteristics of the antigen were determined by western blotting, enzymatic digestion studies, and tunicamycin inhibition studies. Distribution of the antigen in the cultured melanoma cell lines was determined by flow cytometry.

RESULTS

The antigen consists of 2 proteins with molecular mass of 89 and 85 kd. Tunicamycin and enzymatic digestion studies indicated that these proteins contained little glycosylation. Immunogold and immunofluorescence studies localized the antigen to the cell surface. Antigen expression was consistent within each cell line, with > 90% of the cells positive for all cell lines except 1 (80%). Percentage of positive cells and relative intensity of immunostaining were constant throughout all phases of the cell cycle.

CONCLUSIONS

The antigen identified by MAB IBF9 is a well-conserved and highly expressed cell surface protein present during all phases of the cell cycle in all malignant canine melanoma cell lines examined.

CLINICAL RELEVANCE

Because of consistency in expression, the antigen may have potential for use in dogs for melanoma immunodiagnostics and immunotherapy.