CD8A and neurofibromatosis type 1: Such results were confirmed via immunohistochemistry for the T lymphocyte markers CD3 and CD8: the T-cell infiltrates in high-immune NF1-gliomas included cells positive for granzyme B, the cytolytic effector that is upregulated on CD8+ T-cell activation, while B lymphocytes (CD20) and macrophages (CD68) were rare both in high- and low-immune groups [36].