Rebound phenomenon of phytohemagglutinin skin reactivity in leukemia and malignant lymphoma after chemotherapy.

Serial evaluation of host immunocompetence was made by the phytohemagglutinin (PHA) skin test in 13 patients with leukemia and malignant lymphoma, receiving antineoplastic chemotherapy to induce remission. A rebound phenomenon of skin reactivity to PHA was observed after each period of chemotherapeutic treatment in patients with a good response to therapy, but not in patients with a poor prognosis. It is concluded that sequential evaluation of skin reactivity to PHA, as well as in vitro lymphocyte stimulation, is valuable clinically in assessing the progress of malignancies and the response of patients to therapy.