CD4 and melanoma: Analysis of PDAC tissue revealed relatively few T-cell infiltrates as marked by CD3 and CD4 or CD8 staining compared with melanoma.9 This is certainly troublesome, since increased infiltration of CD4+ and CD8+ T cells in tumors is consistently associated with increased survival in patients.8 13–16 This observation parallels immune suppressive features of other tumors, including prostate and breast cancers.