Lymphocyte sensitization in childhood solid tumours and lymphoblastic leukaemia, measured by electrophoretic mobility test.
A modified electrophoretic mobility (EM) test was performed in 150 children to examine their lymphocyte sensitization to myelin basic protein (encephalitogenic factor). Measurements in the cytopherometer were facilitated by using devitalized sheep erythrocytes as indicator particles instead of macrophages. A significant decrease in EM was found in 29/30 children with acute lymphoblastic leukaemia and in 67/75 children with solid tumours, thus giving a false negative rate in malignant disease of 9/105=8-6%, as compared to 6 false positives among 45 children with non-malignant disorders; 5 of the later "false/positive" 6 patients had autoimmune disease. Results of the EM test in the children with leukaemia were compared with those in 9 patients with non-Hodgkin's lymphoma and 2 with Hodgkin's disease at different stages, but no striking change was seen between different diseases, or after cessation of long-term immunosuppressive chemotherapy. Percentage of "slowing" ranged from 4 to 30%. These results indicate that patients with lymphoid malignancies still have lymphocytes which had been sensitized by a common antigen of the malignant cell clone at the beginning of the disease. The EM test, furthermore, could serve as an additional diagnostic aid in differentiating benign from malignant masses in the abdomen, extremities or intracranial disease.