CD4 and neoplasm: Later, an immunohistochemical and immunofluorescence study of 54 chordoma samples for PD-1, PD-L1, CD3, CD8, CD4, CD20, and FOXP3 expression showed PD-L1 tumor cell expression in almost 70% of the cases and suggested that the higher infiltration of CD3, CD8, and CD4 T cells is a positive prognostic factor [10,11,12,13,14].