"Plasmacytoid T cells" in Castleman's disease. Immunohistologic phenotype

Plasmacytoid T cells in two cases of Castleman's disease were stained with a panel of monoclonal antibodies to hematopoietic cell-associated antigens, using an immunoperoxidase technique on frozen sections. The immunohistologic phenotype of these cells was T4/Leu-3+, HLA-DR+, T1/Leu-1-, T3/Leu-4-, T8/Leu-2-, T11/Leu-5-, B1-, B2-, Leu-14-, Ig-, CALLA-, OKM1-, Leu-M1-. In contrast to plasma cells of B lineage, plasmacytoid T cells were T200+, T10-. The phenotype was similar to that of two previously reported lymphomas of plasmacytoid T cells. Plasmacytoid T cells appear to be a unique subset of lymphoid cells, whose function remains to be established.