Positive cellular localization: cell membrane
CD4 is a glycoprotein, belongs to the immunoglobulin superfamily related to HLA class II antigen recognition. In lymphoid tissue, there are a large number of CD4 + T cells in the perifollicular area, and a small number of CD4 + T cells in the germinal center and mantle. CD4 is also expressed in sinusoidal cells, monocytes and monocyte derived cells. CD4 plays an important role in the classification of lymphocytes and malignant lymphoma.