LYSOZYME INDUCED RECOVERY OF THE RESPONSE TO CONA ON MONONUCLEAR-CELLS HARVESTED FROM MICE BEARING MCA MAMMARY-CARCINOMA

The effects of lysozyme (hen egg-white lysozyme) on lymphocytes harves ted from mice bearing MCa mammary carcinoma were tested at the daily d ose of 100 mg/kg given orally for 10 consecutive days. With this exper imental paradigm that consists of a significant reduction of lung meta stasis formation, lysozyme was seen to be capable of stimulating the r ecovery of the response to ConA of mononuclear cells, reduced by tumor growth; this effect was particularly evident with splenocytes and GAL T lymphocytes. The effects of lysozyme depended: (i) on the presence o f plastic adherent cells, (ii) at least in in vitro experiments, on th e amount of lysozyme used, being higher at the dose of 250 mug/ml of i ncubation mixture, and (iii) on the time of challenge with lysozyme. T hese effects were shown either by measuring the [H-3]-thymidine incorp oration into DNA or by application of the sulphorhodamine test for pro tein synthesis. After in vivo treatment, lysozyme significantly modifi ed the histological architecture of the mucosal immunity of the gut, b y causing a significant reduction of the number of the lymphatic nodul es placed immediately under the layer of epithelial cells of villi. At the same time no significant modification of Peyer's patches was note d. Together these data stress the role of lysozyme in the modulation o f host immunity and, in particular, point out the relevance of the muc osal immunity of the gut as first target for lysozyme activity.