T-cell infiltration of primary CNS lymphoma

We stained 13 primary CNS lymphomas (PCNSLs) (six from patients with AIDS, seven from immunocompetent patients) with a panel of antibodies to T cells (pan T cell [CD3], T helper cell [CD4], T suppressor cell [CD8], delta/delta cell [CD4-8-]), B cells (CD20), hematopoietic cells (T200), and NK cell (CD56). We estimated the percentage of tumor cells staining with each antibody. All tumors were B-cell lymphomas. The non-AIDS tumors showed a significant infiltration with CD3+ cells (mean of 10.82% of total cells). The AIDS patients' tumors showed a smaller percentage of CD3+ infiltrating cells (mean, 4.88% of total cells) (p<0.01). CD4+ cells were 9.11% of the total hematopoietic cells in the non-AIDS patients and 3.13% in AIDS patients (p<0.01). AIDS patients showed some CD8+ cells (0.3%), which was significantly higher than in immunocompetent patients (0%) (p<0.05). Very few tumor cells stained with the NK cell and delta/delta cell markers. Both immunocompetent and AIDS patients with PCNSL exhibit significant CD3+ and CD4+ cell infiltration of their tumors; this infiltration is significantly lower in AIDS patients. AIDS patients show a minor CD8+ cell infiltration of their tumors. These results on PCNSL are different from systemic lymphomas, which show a higher CD4 and CD8 cell infiltration, and may offer insights into the more aggressive nature of AIDS-related PCNSL.