In situ immunologic phenotyping of mycosis fungoides.

In situ immunologic phenotyping of the cutaneous lymphoid infiltrates of five cases of mycosis fungoides (MF) was performed. This was done by the immunoperoxidase technic using monoclonal antibodies directed against normally expressed by mature peripheral T cells and T cells subsets. A significant proportion of the infiltrates reacted with peripheral T cell antibodies. In addition, "helper" predominance was demonstrated. However, cells reacting positively with "suppressor" antibodies were also demonstrated in three cases, indicating immunologic heterogeneity of the infiltrates. The presence of a significant component of the infiltrates yielding an equivocal or negative reaction with the mature T cell antibodies, especially in the infiltrates of one case which had a fatal outcome, suggests further heterogeneity with the presence of immature cells. Future investigation with monoclonal antibodies directed against immature T cell differentiation antigens will be of interest.