Antibody secreting cell probes (ASC-probes) were generated from the hepatic lymph node (HLN), mesenteric lymph node (MLN) and spleen of rats after infection with the liver fluke, Fasciola hepatica, and used to probe Western blots of parasite antigens. In chronic primary infections, parasite-specific antibodies were only detected in ASC-probes derived from HLN. Seven days after a secondary infection, a restricted response was detected in ASC-probes from the MLN, directed predominantly against an antigen specific to the newly excysted juvenile (NEJ) stage. This NEJ-specific antigen was only recognized by HLN if the second infection was not rejected and the challenge flukes reached the liver. Measurement of the immunoglobulin levels present in the ASC-probes showed significant elevation only in lymph nodes draining sites of recent infection. In addition, when the isotype profiles were determined in ASC-probes derived from different lymph nodes, it was observed that they showed different isotype preferences, in particular IgA for the MLN, IgE for HL.N and IgM for spleen. These results show that discrete and independent immune responses occur in different body compartments of a rat against different stages of a parasite.