Serum antibodies against feline oncornavirus-associated cell membrane antigen in cats bearing virally induced uveal melanomas.

The humoral immune response to a virally induced feline model of human uveal melanoma was studied by examining sera from cats bearing iridal and choroidal melanomas for antibody to the feline oncornavirus-associated cell membrane antigen (FOCMA). Anti-FOCMA antibodies appeared earlier and in higher titers in cats that ultimately expressed nonprogressing uveal melanomas. By 8 weeks after virus inoculation 56% of the cats with nonprogressing lesions had anti-FOCMA antibodies, whereas only 7% of the cats with progressive tumors produced demonstrable antibodies against FOCMA. Mean serum antibody titers were approximately 10 times higher in cats with nonprogressive lesions than in cats with progressive tumors. Similar trends were observed throughout the 28-week study period. Early appearance and a high titer of serum antibody against FOCMA correlated with nonprogressing uveal melanoma. The results indicated that uveal melanomas could be immunogeneic and successfully managed by the host's immune system.