Dr. Kassai Tibor szerk.: Parasitologia Hungarica 2. (Budapest, 1969)

more profound inhibition may occur locally at the site of production of worm antigen i.e. in the immediate vicinity of worms present on the surface of the intestinal mucosa. SYMONS and PAIRBAIRN also comment on a local effect of the products of parasites, namely that their presence induces Ca

++ accumulation within epithelial cells resulting in decreased oxidative phosphorylation and reduced synthesis of high energy compounds (ATP etc) in the mitochondria. Accordingly, there is a decrease in the activity of enzymes (alkaline phosphatase, leucinaminopeptidase) produced by the mucosal epithelial cells. The in vivo enzyme inhibition of metabolic products of the parasite may be sufficient to prevent degradation of the active determinant groups of the antigen molecules. Since this process is considered to take place in the immediate vicinity of the intestinal mucous membrane such molecules should easily reach the surface of the absorbing epithelial cells. However, the interaction of digestive fluid and worm antigen may result in partial breakdown of the antigen molecules. Provided this does not extend to the active determinant groups it may serve as a further important factor in the process of immunization by promoting the production of smaller sized molecules that are known to be more readily absorbed through the uninjured intestinal epithelium than are larger ones (TÓTH, 1966; BERNSTEIN and OVARY, 1968). Summary The authors demonstrate that the metabolic products of N

. bra siliensis can inhibit the proteolytic activity of rat intestinal fluid. The interaction of worm antigen and the enzymes may have an importance in. the survival, absorption, or eventual production of active antigen molecules.