The Kurloff cell in estrogenized guinea pigs as a CT7+ 8BE6- CT6- MR-1- CT10- IgM- lymphocyte with natural killer activity.

The relationship of the Kurloff cell (KC), guinea pig blood mononuclear cell with natural killer (NK) activity, to a known cell lineage was established. Using indirect immunoperoxidase staining and flow cytometric analysis, numerous monoclonal antibodies directed against guinea pig macrophage antigen, Ia antigen or different T lymphocyte markers and a polyclonal anti-IgM serum were tested in unimmunized estrogenized animals. We excluded any relationship between KC and the monocytic macrophage lineage (MR-1-) and between KC and the B lymphocyte lineage (CT10- and IgM-). The KC immunophenotype was pan T CT7 positive but 8BE6 (mature thymocyte) and CT6 (cytotoxic suppressor T lymphocyte) negative. Since KC displays an NK activity, this cell may be classified among the NK effector cells exhibiting some T lymphocyte markers.