Role of levamisole as immunomodulant in mouse lymphoma model

Levamisole (LMS) has been considered an immunorestorative agent capable of enhancing host's antitumor immune responses. Clinical studies showed that LMS plays a significant role in adjuvant chemotherapy of colorectal cancer. Therefore studies were performed to test whether LMS would be able to restore graft responsiveness in mice with drug-dependent, age-dependent or virus-dependent immunodeficiency. The results show that LMS has little or no influence on the limited antitumor effects of Dacarbazine or Ara-C in mice bearing allogeneic leukemias (i.e. in a host-tumor model in which immuno-chemotherapy synergism occurs with less immunodepressive anticancer drugs). Moreover LMS does not alleviate allograft response inhibition produced by high-dose Dacarbazine or by a mouse RNA virus. However the agent restored graft responsiveness in aged animals. The limited immunoenhancing effects of LMS, as detected in the present study, suggest that the clinical efficacy of the agent could be due to mechanisms not entirely related to its immunopharmacological properties.