Primary malignant lymphoma of the brain: an immunohistochemical study of eight cases using a panel of monoclonal and heterologous antibodies.

Frozen sections of eight primary malignant lymphomas of the brain were examined by the immunohistochemical methods using a panel of monoclonal and heterologous antibodies to B lymphocyte (immunoglobulins, BA-1, Leu-12 and HLA-DR), T lymphocyte (OKT-11 and Leu-1) and monocyte (OKM-1) surface markers. Paraffin sections were also used in the examination of cytoplasmic immunoglobulins. Surface and/or cytoplasmic immunoglobulins (Ig) were observed in seven cases, four of which were shown to be distinctly monoclonal and the other three less so. The remaining 1 case showed no distinct staining for Ig. BA-1, Leu-12 and HLA-DR stainings were positive in four, four and five cases, respectively. The marker phenotypes of (BA-1, Leu-12, HLA-DR) were shown to be (+, +, +) in one lymphoma, (+, -, -) in three, (-, +, +,) in three, and (-, -, +) in one. Thus, it was demonstrated that the present lymphoma cases showed a marked immunological heterogeneity, and it was shown that all of them including the Ig-negative case revealed one or more of these three additional B cell markers, indicating B cell lineage of these cases. Examination of T cell and monocyte markers revealed positive staining in normal or reactive lymphoid cells distributed around blood vessels or sporadically in tumor tissues, but not in lymphoma cells. Epstein-Barr virus (EBV)-associated nuclear antigen was not demonstrated in the seven cases examined, making it unlikely that these lymphomas were related with EBV infection.