CD27 and melanoma: Analysis of NK cell subsets, based on the cell surface expression profiles of CD11b and CD27, indicated a significant decrease in mature subsets, CD27+CD11b+ (p < 0.001) and CD27-CD11b+ (p < 0.01), and an increase in the immature NK cell subsets, such as CD27-CD11b- (p < 0.05) and CD27+CD11b- (p < 0.01), for the melanoma-bearing mice (MbM) group compared to the control group.