Gao Y, et al. - In this secondary analysis of a cohort study of 10,649 organ transplant recipients, researchers examined the relationship between HLA antigen mismatch and skin cancer incidence following a solid-organ transplant. Among heart and lung transplant recipients, the HLA antigen mismatch seems to be related to reductions in the risk of skin cancer after solid-organ transplant. The results obtained from this retrospective cohort study indicate that HLA antigen mismatch activates the tumor surveillance mechanisms in transplant recipients that protect against skin cancer and that the risk of skin cancer might be higher in patients receiving a well-matched organ. The most statistically significant mismatch for skin cancer risk was the degree of HLA-DR mismatch, but not HLA-A or HLA-B mismatch.