Functional studies of lymph nodes infiltrated by non-Hodgkin's lymphoma

Cell cultures have been carried out using lymphoid cell suspensions derived from non-neoplastic human lymph nodes and nodes involved by non-Hodgkin's lymphomas. Two mitogens, phytohaemagglutinin (PHA) and/or pokeweed mitogen (PWM), were added to the cultures and the cytological changes assessed by light and electron microscopy. PHA was found to transform lymphocytes into larger cells whose ultrastructural features closely resembled those of germinal centre cells and some tumour cells found in malignant lymphomas. After 3 days' stimulation of malignant lymphoma cells with PWM, a cell population emerged with ultrastructural features similar to those cells described after 5-7 days stimulation of normal lymphocytes by PWM. Malignant lymphoma cells may thus be partially stimulated and possibly arrested at a certain stage in their transformation.