THE EFFECT OF YOGURT ON THE CYTOTOXIC AND PHAGOCYTIC-ACTIVITY OF MACROPHAGES IN TUMOR-BEARING MICE

In a previous paper, it was demonstrated that feeding yoghurt was able to inhibit the growth of an intestinal tumour induced chemically with 1,2-dimethylhydrazine (DMH). This effect was due to the increase in I gA-producing cells and a diminution of the inflammatory immune respons e. In this paper the phagocytic and cytotoxic capacity of macrophages both involved and not involved in the target organ are studied. The st udy was aimed at determining whether in the intestinal tumour inhibiti on demonstrated previously the systemic immune response was also incre ased. The cytotoxic capacity and beta-glucuronidase enzyme levels of t he peritoneal macrophages were analyzed together with the cytolytic ef fect of the serum on tumour cells and the phagocytic activity of the m acrophages infiltrating the intestinal mucosa. Groups of mice were spl it into three experimental groups. One group was treated with DMH. The others were treated with DMH, and their diets were supplemented with yoghurt for 7 or 10 consecutive days, during 24 weeks. It was demonstr ated that feeding yoghurt for 7 or 10 days increased cytotoxic and bet a-glucuronidase levels in peritoneal macrophages, and also the cytolyt ic capacity of serum, reaching values significantly higher than those in the DMH control. Enhancement of the phagocytic activity of the macr ophages associated with the large intestine was also observed This inc rease in the macrophage activity involved in the systemic and mucosal immune responses could also be responsible for the tumour inhibition o bserved in the group of mice fed with yoghurt. The presence in the ser um of lytic factors (cytokines) which were released by immune cells ac tivated by feeding yoghurt may also have had a role in tumour inhibiti on.