The importance of the dendritic cell for the capture of antigens and i
nitiating an immune response is now well recognized. Whereas much is k
nown about their structure and function, their lineage is still not cl
ear. Studies in vitro have demonstrated that the regulated maturation
of function that occurs in culture explains many of the in vivo events
relating to antigen capture and presentation. The control over matura
tion and migration of these cells to the immune system is decisive as
to whether an immune response is mounted or not. 'Danger' signals prov
ided by conserved bacterial products or by microenvironmental cytokine
s are important regulators. Dendritic cells have been clearly involved
in the development of respiratory disease and our understanding of th
eir involvement will have an impact on our future therapeutic strategi
es. (C) 1996 Academic Press Limited