CYTOKINE MESSENGER-RNA EXPRESSION AND IFN-GAMMA PRODUCTION IN NEMATODE RESISTANT AND SUSCEPTIBLE LINE LAMBS ARTIFICIALLY INFECTED WITH GASTROINTESTINAL NEMATODES

The mRNA expression of the cytokines interleukin (IL)-2, IL-4 and inte rferon (IFN)-gamma and the production of IFN-gamma was examined in mes enteric lymph node cells (MLNC) and CD4(+) enriched cells populations from resistant and susceptible line lambs by use of reverse transcript ase-polymerase chain reactions (RT-PCR) and ELISA. MLNC obtained from lambs that were previously infected with a mixed gastro-intestinal nem atode population were stimulated with Con A or Trichostrongylus colubr iformis specific antigen. Four weeks after infection MLNC from both li ne lambs expressed high levels of mRNA coding for IL-2, IL-4 and IFN-g amma. MLNC from resistant line lambs when stimulated with antigen for one day had higher mRNA expression of IL-2 and IFN-gamma and after thr ee days of culture had higher levels of IL-4 mRNA than MLNC from susce ptible line lambs. Antigen stimulated MLNC of resistant line lambs had a higher IFN-gamma production than those from susceptible line lambs. These results indicate that in resistant line lambs the secondary in vitro responses of cytokine mRNA and IFN-gamma production to nematode specific antigen differs from those of susceptible line lambs.