http://www.niaid.nih.gov/final/immun/immun.htm
(from NIH)
 
http://www.niaid.nih.gov/final/immds/immds.htm
(immunologic diseases from NIH)
 
http://www.cancerresearch.org/immhow.html
(from Cancer Research Institute)
 
http://www.niaid.nih.gov/publications/autoimmune/work.htm
( autoimmune disease from National Institutes of  Health)
 
http://www.sciencemuseum.org.uk/exhibitions/lifecycle/112.asp
 and
http://www.sciencemuseum.org.uk/exhibitions/lifecycle/105.asp
(from a British Science Museum -- with great images)
 
http://www.cdc.gov/nip/publications/fs/gen/howvpd.htm
(from CDC)
 
http://www.canadian-health-network.ca/servlet/ContentServer?
cid=1007411&pagename=CHN-
RCS%2FCHNResource%2FFAQCHNResourceTemplate&c=CHNResource&lang=En
(from Canadian Health Network)
 
Hope that these help remove some confusion.
[Posted in FML issue 4641]