Linoleic acid, which is known to affect the immune response, was present at ~0.6% in the 12% fat diet and ~2.6% in the 6% fat diet. The latter results – taken together with the considerable body of literature implicating specific isomeric forms of various dietary lipids, including linoleic
acid, as immune system modulators [62, 63] at levels comparable to those in the mouse diets we used  and with findings that different dietary lipids can affect the process of infection with Listeria monocytogenes [64–66] – suggest that dietary factors, possibly lipid composition, may affect the outcome of C. jejuni infection in C57BL/6 IL-10-/- mice. The manufacturer of the mouse chow we used does not report the isomeric composition of the total linoleic acid, which is derived from fish meal, soybean, and grains, Trichostatin A supplier and which might be expected to vary from batch to batch. It would therefore be difficult or impossible to determine retrospectively whether the chow fed to the mice in the three experiments was different in composition. Finally, it is also possible that the differing
constituents of the two diets influenced either the host immune system or the indigenous intestinal microbiota or both in such a way as to affect the pattern or level of disease expression due to C. jejuni infection. Experiments using mice fed defined Ku-0059436 in vivo diets would be required to explore these effects. There was no indication from the ELISA results that antibody responses were protective in C57BL/6 IL-10-/- mice against infection with any of the tested strains of C. jejuni used for challenge. The majority of infected mice produced robust Th1 associated IgG2b responses
to all C. jejuni strains tested; this response was associated with disease except in strains D2586 and NW. Infected non-colonized mice did not produce strong IgG2b responses. Also, other antibody responses in plasma of all infected mice were low. However, there were some significant Phospholipase D1 differences between the first and last passage in levels of anti-C. jejuni 11168 IgG2b antibodies detected by ELISA in mice MAPK Inhibitor Library challenged with various C. jejuni strains. We suspect that these differences reflected changing surface antigenic structures of the C. jejuni strains during repeated passage that made them more or less similar to antigen from the unadapted 11168 strain used to coat the ELISA plates. Thus, strain 11168 changed over passage so that mice in the last passage had significantly less anti-non-adapted 11168 IgG2b antibodies than mice in the first passage. This speculation would have to be followed up with further experiments to test this hypothesis. In contrast, mice challenged with strain D2586 in the fourth passage produced IgG2b antibodies that recognized non-adapted strain 11168 ELISA antigens better than mice in the first passage experiment. In addition, there was no correlation between any immunoglobulin isotype and colonization (rank abundance) of any C.