In situ-differentiation of lymphocytes in fixed tissues with peroxidase-labeled Helix pomatia lectin: revelation of the Helix pomatia lectin receptor on cell surfaces. Application in lymph node tissues and cutaneous lymphomas.

A receptor for Helix pomatia lectin (HPL) occurs on 71.5% of peripheral blood lymphocytes. With double incubation techniques we could show that the population of HPL-positive lymphocytes is by far (greater than 90%) identical with the population of T lymphocytes, as determined by "classical" markers (E rosetting) and newly developed T cell markers like OKT3 or anti-human Lyt3 monoclonal antibodies. In formaldehyde-fixed lymph node sections we could demonstrate the homing area of HPL-positive lymphocytes, the paracortical regions. Conventional histological counterstaining was readily possible. We have employed HPL-peroxidase for differentiation of lymphocytes in benign and malignant infiltrates in human skin. In reactive cutaneous infiltrates, as well as in cutaneous lymphomas, HPL-peroxidase staining allows a clear differentiation of the involved lymphatic cells, and may serve as a tumor marker in certain T lymphomas, where we could demonstrate the lymphoma cells to carry the HPL-receptor.