Abstract
Mucosae are constantly bombarded with foreign substances and micro-organisms and must therefore be protected by appropriate defence mechanisms reffered as mucosal immunity. Protective responses at mucosal surfaces differ in some ways from systemic immunity.
These differences are discussed in this article. The attempts to prevent infectious diseases involving mucosal surfaces by modulating the immune system were made almost 100 years ago and over the last number of years new strategies for mucosal immunization have evolved.