Regional immune responses with stage-specific antigen recognition profilesdevelop in lymph nodes of pigs following Ascaris suum larval migration

The early life-cycle of the pig round worm, Ascaris suum, involves well-def ined larval development in the liver; lungs and finally the small intestine . Distinct regional immune responses to larval antigens of A. suum were obs erved in the draining lymph nodes of immunized and challenged pigs during l arval migration. This was reflected in a transient enlargement of the stimu lated lymph nodes, due to increases in numbers of B cells and CD4 T cells, and the production of A. suum-specific antibody by antibody secreting cell (ASC) cultures. Larval antigen recognition pattern of antibodies in serum, bile and draining lymph node ASC culture supernatant (ASC-probes) was exami ned by immunoblotting. This revealed distinct organ-specific recognition pa tterns of larval-specific antigens by the draining lymph nodes at different times after challenge. In particular an early larval 42 kDa antigen was re cognized specifically by ASC-probes of the liver lymph nodes at 7 but nor 1 4 days postchallenge (pc) which was not detected in other lymph nodes, seru m or bile of the same pig. Similarly, a late larval antigen of 34 kDa was u niquely detected by lung and jejunal ASC-probes at 14 days pc. These observ ations demonstrate how development of distinct regional immune responses in tissues with different antigen stimulation cart be monitored with ASC-prob es and flow cytometry.