CD200 and melanoma: First, in two correlation studies, CD200 mRNA expression in malignant cells has been shown to be associated with decreased survival of patients [9], [10]; Second, CD200-expressing melanoma and ovarian cancer cells downregulate Th1 cytokine production when co-cultured with allogenic leukocytes [7], [21] and anti-CD200 antibody treatment can enhance tumor rejection by peripheral blood mononuclear cells in a hu-SCID adoptive transfer model [22], [23]; Third, in a recent study, CD200 expression was found to be positively correlated with the metastatic capacity of squamous cell carcinoma [24].