Mucosal Immunization with Antigen-containing Microparticles
The Common Mucosal Immune System The significance of inducing not only systemic immunity but also good local immunity at susceptible mucosal surfaces has been recognised only recently. Traditionally, vaccines have been administered parenterally to evoke antibody production and cell-mediated immunity in systemic tissues and in the blood. However, the delivery of antigens at mucosal surfaces may stimulate immune responses in both systemic and mucosal compartments due to the dissemination of antigensensitised cells to other tissues (Moldoveanu et al., 1993). It has been shown that protection against influenza correlates better with the presence of antibodies at the mucosal surfaces than with serum antibodies, implying that the majority of the infections affect or start from the mucosal surfaces. Most bacterial and viral diseases gain entry into the host via mucosal tissues including cholera, plague and Human Immunodeficiency Virus (HIV) (Mestecky et al., 1994). The induction of an immune response exerting its effect at the mucosal site of entry, while capable of translation to distant mucosa and secretions, would lead to a more effective vaccination against pathogens (Bienenstock, 1988). Mucosal
1Unidade de Ciências e Tecnologia Farmacêuticas, Faculdade de Farmácia, Universidade de Lisboa, Av. das Forçs Armadas, 1600 Lisboa, Portugal 2Pharmaceutical Sciences Institute, Aston University, Aston Triangle, Birmingham B4 7ET, UK
sites possess a large area of contact with the environment and are often exposed to antigenic substances that induce specific humoral as well as cell-mediated immune responses, not only at the site of stimulation, but also in the draining lymph nodes, spleen and bone marrow.