[In situ - demonstration of helper-T-lymphocytes in cutaneous malignant lymphomas by diaminopeptidase IV (DAP IV)].

Demonstration of helper-T-lymphocytes in tissue sections of cutaneous lymphomas by diaminopeptidase IV (DAP IV) gives new informations concerning the composition of these malignant infiltrates. It can be demonstrated that in plaque stage of mycosis fungoides the majority of T-lymphocytes are helper cells, thus giving evidence that mycosis fungoides represents a helper-T-cell-lymphoma. In tumor stage DAP IV activity changes, and the number of DAP IV-positive cells decreases remarkably. In malignant B-cell-lymphomas and high grade malignant lymphomas a small percentage of the infiltrate is composed of helper-T-lymphocytes; their existence was not known before. This method permits easy and reproducable identification of helper-T-lymphocytes in dermal infiltrates.