Lymphocyte transformation in children with neuroblastoma.

Using a simple fingerstick-whole blood technique, we demonstrated that patients with disseminated neuroblastoma have diminished lymphocyte responses to phytohemagglutinin (PHA) and that their sensitivity to antilymphocyte serum inhibition of PHA responses was increased over that of tumor-free controls. These altered immunologic reactivities led us to question the chronologic sequence between the occurrence of the tumor and the lymphocyte defect. Tumor-bearing patients had serum substances that exerted an inhibitory effect on the transformation responses of lymphocytes from unrelated normal individuals; these substances may be present in sera for long periods after the tumor is eliminated.