CD33 and meningioma: CD45+ inflammatory cells that infiltrated meningiomas mainly included tissue macrophages (TiMa) with an HLA-DR+CD14+CD45+CD68+CD16−/+CD33−/+ phenotype and a high phagocytic/endocytic activity, together with a smaller population of cytotoxic lymphocytes, mostly CD8+ T cells and NK-cells [10].