Bovine ocular squamous cell carcinoma: tumor-associated immunity detected by E-rosette augmentation test

The E-rosette augmentation (ERA) assay was used to study cell-mediated immunity with blood leukocytes from cattle with bovine ocular squamous cell carcinoma (BOSCC), from cattle with benign ocular or cutaneous lesions, and from healthy controls. Potassium chloride extracts (3 M) of BOSCC and skin from the same donor, cutaneous bovine papillomas, allogeneic lymphosarcoma, and xenogeneic sheep squamous cell carcinoma were used as antigens. Of the 21 animals with BOSCC, leukocytes of 19 gave positive ERA reactions to BOSCC extract and only those of 4 reacted nonspecifically to other extracts. Of 21 animals in the control group, only 3 gave positive ERA reactions. In reciprocal tests, cattle with BOSCC showed ERA reactivity only against extracts of BOSCC, and cattle with cutaneous papillomas showed reactivity only against extracts of cutaneous papillomas. Blood leukocytes from tumor-bearing cattle stimulated with related tumor extracts released a soluble factor that enhanced E-rosette formation when tested on normal bovine leukocytes.