CD4 and neoplasm: Studies have shown that whether in CD4+ T-cell-deficient mice or CD8+ T-cell-deficient mice, the blood vessels were structurally and functionally abnormal, with the CD4+ T-cell-deficient mice particularly decreasing pericyte coverage and increasing permeability of the blood vessels, whereas manual injection of CD4+ T cells into tumor-bearing mice increased pericyte coverage of the blood vessels and reduced hypoxia, indicating the occurrence of tumor vascular normalization (238, 240).