[An immunohistochemical study of Ki-67 expression of brain tumor cells and mononuclear cell subsets infiltrating these tumors].

Fifty-one brain tumors were studied by immunohistochemical methods. The densities of CD45RO+, CD4(OPD4) and CD8 T cells infiltrating the tumors showed negative correlation with the tumor size and positive correlation with the density of macrophages. The density of Ki-67+ tumor cells rose along with the increase in tumor malignancy and showed positive correlation with the tumor size and negative correlation with the density of CD4 T cells. The CD4/CD8 ratio was 0.853, far lower than the normal ratio and there was also positive correlation between their densities. The above results suggest that the level of Ki-67 expression can objectively reflect the proliferative rate and malignant grade of brain tumors. The CD45RO+, CD4 and CD8 T cells infiltrating brain tumors are able to directly inhibit tumor growth. The macrophages take part indirectly in the immunoresponse against brain tumors by influencing CD4 and CD8 T cells. Brain tumors may inhibit the proliferation and immune function of the CD4 subset.