Lymphocyte stimulation in the cellular inflammatory reaction of some human skin tumours.

By labelling dermal infiltrate cells with H3-thymidine, two types of skin tumours can be distinguished: one type with many labelled cells in the infiltrate (H3-thymidine labelling index, H3-I), the other with few labelled cells. Type I includes malignant melanoma (H3-I = 2.2%) and hemangioendothelioma (2.8%). Type II includes metastases of malignant melanoma (1%), squamous cell carcinoma (1.1%), basel cell epithelioma (0.5%), nevus cell nevus (0.6%), and nevoid lentigo (0.4). The number of labelled cells in the cellular reaction of Type II tumours does not differ significantly from that in normal human corium (0.75%), though there may be a dense cellular reaction. DNA-synthesizing cells were classified with the aid of characteristical stainings and histochemical methods. A vast majority of them were found to be lymphocytes. Our research underlines the special importance of cellular inflammatory reaction, i.e. cellular immunity, im malignant melanoma and probably in hemangioendothelioma.