Immunohistochemical and in vitro functional analysis of pineal-germinoma infiltrating lymphocytes: report of a case.

The present study describes the phenotypic and functional analysis of tumor-infiltrating lymphocytes isolated from a germinoma located in the pineal region. Tumor-infiltrating lymphocytes were separated from the germinoma and cultured in medium containing IL-2 (1000 U/ml). An immunohistochemical analysis of frozen sections revealed that 90% of the germinoma-infiltrating lymphocytes were CD3-positive T cells expressing CD4, CD8, and HLA Class I and Class II antigens, but were negative for CD16, CD20, CD23, CD25 and CD14 antigens. After in vitro cultivation in the presence of high concentrations of IL-2, the lymphocytes proliferated for 2 weeks, showing marked DNA synthesis. In addition, the lymphocytes could lyse NK-resistant allogeneic target cells. These results provide evidence for a potential role of germinoma-infiltrating lymphocytes in vivo, and suggest that the lymphocytes may control the growth of autochthonous tumor cells by killing those that are not restricted to the major histocompatibility complex.