Cutaneous vaccination: the skin as an immunologically active tissue and the challenge of antigen delivery

Vaccination is one of the major achievements of modern medicine. As a resul t of vaccination, diseases such as polio and measles have been controlled a nd small pox has been eradicated. However, despite these successes there ar e still many microbial diseases that cause tremendous suffering because the re is no vaccine or the vaccines available are inadequate. In addition, eve n if vaccines were available for all infectious diseases there is no guaran tee that people would use them routinely. One of the major impediments to e nsuring vaccine efficacy and compliance is that of delivery. Presently most vaccines are given by intramuscular administration. Unfortunately this is often traumatic, especially in infants. Thus, if it was possible to replace intramuscular immunization by mucosal (oral/intranasal) or transdermal del ivery it may be possible to both enhance mucosal immunity as well as improv e overall compliance rates. The transdermal route has been used by the phar maceutical industry for the delivery of various low molecular weight drugs. Some of the approaches used for smaller compounds may also have potential for delivery of either protein or polynucleotide vaccines. However, there i s a greater challenge to delivering large molecular weight molecules throug h the skin due to size, charge and other physicochemical properties. This r eview will describe the recent advances that have been made in dermal and t opical delivery as related to vaccines. (C) 2000 Published by Elsevier Scie nce B.V. All rights reserved.