Lysozyme stimulates lymphocyte response to ConA and IL-2 and potentiates 5-fluorouracil action on advanced carcinomas.

The oral administration of 100 mg/Kg/day of hen egg-white lysozyme (Lysozyme) for 8 consecutive days to mice bearing advanced MCa mammary carcinomas and treated with 5-fluorouracil (5-FU) increases the efficacy of 5-FU on primary tumor growth and on lung metastasis formation and particularly on the postsurgical survival time. These effects are accompanied by the correction of the reduced in vitro response to ConA of lymphocytes obtained from the spleen of the treated mice. In vitro, lysozyme is capable of inducing proliferative activity in a population of blast cells, obtained by a mixed population of mononuclear cells harvested from the spleen of healthy mice, and of evoking a marked proliferative effect to IL-2 in a condition in which, in lysozyme untreated lymphocytes, IL-2 is completely uneffective. These data stress the effects of lysozyme on host immunity following oral administration and moreover indicate the beneficial role of this peptide in conditions in which the increase of host responses can significantly contribute to the success of the treatment.