Efforts to design effective mucosal vaccines have been hampered by an
incomplete understanding of factors controlling the development of muc
osal immunity. It is now clear, however, that T cell-derived cytokines
play a major role. Recent developments in 'gene knockout' technology
have allowed the generation of strains of mice in which particular gen
es have been inactivated. The availability of mice rendered deficient
for production of Th2 cytokines has facilitated studies of the inducti
on and development of mucosal immune responses in the absence of these
factors. We have used several genetic approaches. including cytokine-
deficient mice and recombinant vectors constructed to express genes fo
r a range of different cytokines, to demonstrate the importance of the
se factors in the mucosa. Such genetic approaches appear to represent
powerful tools for in vivo studies of the influence of cytokines in mu
cosal immunoregulation.