CD200 (OX-2 Membrane Glycoprotein) is Expressed by Follicular T Helper Cells and in Angioimmunoblastic T-cell Lymphoma

CD200, an immunoglobulin superfamily membrane glycoprotein, is expressed in B cells, a subset of T cells, and in a range of B-cell lymphoproliferative disorders. We recently found, by immunohistochemical staining, that follicular helper T cells associated with neoplastic L and H cells in nodular lymphocyte predominant Hodgkin lymphoma, express CD200. Here we show that CD200 is expressed by follicular helper T cells in reactive lymphoid tissue, using single-color and 2-color immunohistochemical staining. Immunohistochemical staining of a range of T-cell lymphoproliferative disorders shows that the neoplastic cells in angioimmunoblastic T-cell lymphoma are immunoreactive for CD200, and the pattern of expression is similar to that of other follicular helper T-cell markers, PD-1 and CXCL13. In contrast, only a minority of cases of T-cell neoplasms other than angio-immunoblastic T-cell lymphoma are immunoreactive for CD200. A subset of CD200-positive peripheral T-cell lymphoma, not otherwise specified, cases may represent evolving angioimmunoblastic T-cell lymphoma or another neoplasm derived from follicular T helper cells. We conclude that CD200 is a useful immunophenotypic marker of angioimmunoblastic T-cell lymphoma and may be a suitable therapeutic target for an anti-CD200 immunotherapy undergoing clinical trial.