Local IL2 and IL12 treatment of Bovine Ocular Squamous Cell Carcinoma (BOSCC) and Bovine Vulval Papilloma and Carcinoma Complex (BVPCC) in Cattle in Zimbabwe

Abstract

Effect of local IL-2 application on bovine cancer In tropical countries there is an increased prevalence of two important cancers in cattle: Bovine Ocular Squamous Cell Carcinoma (BOSCC) and Bovine Vulval Papilloma Carcinoma Complex (BVPCC). Both cancers are associated with increased annual hours of sunshine, increased altitude and decreased latitude. These cancers occur in unpigmented skin where there is no or limited hair; skin pigment and hair appear to protect against cancer induction by sunshine. These cancers occur in about 10 percent of cattle in tropical countries but only rarely in moderate climates. The veterinarian Rachel Stewart has treated both types of cancer with peritumoral or intratumoral Interleukin-2 (IL-2) injections in Zimbabwe. This locally injected IL-2 induces leakage of fluid from local capillaries, causing oedema. This leads to enhanced tissue pressure that inhibits blood flow in the capillaries. As a consequence cancer cells die. The necrotic tumour material is phagocytosed by white blood cells. This leads to antigen presentation and consequently tumour immunity. This causes further tumor cell killing. Treatment of BOSCC with local IL-2 application leads to gradual tumor regression. After about 6-9 months Complete Regression is obtained in up to 69% of the cases. Treatment of BVPCC leads to stable disease in up to 73% of the cases. It is understandable that the BOSCC is more susceptible to IL-2 as there are more blood capillaries in BOSCC than in BVPCC. In addition up to 14% of BOSCC will be eliminated by the animals’ own immune response without treatment whereas no spontaneous regression is seen with BVPCC. These results are economically important as cows will live longer without a tumour; produce more calves and more milk during their extended life time. In addition slaughter carcasses will have more value if there is no tumour evident. The treatment is easy and can be performed at the farms. The treatment is cheap as only small quantities of IL-2 are needed.