Interferon release as a measure of the T-cell response to coccidial antigens in chickens.

Spleen cells from chickens which had been immunised with Eimeria tenella secreted interferon within 24 h of stimulation with as little as 10 microg antigen per millilitre from E. tenella oocysts. Secretion of interferon by spleen cells first occurred at the time immunity was developing but after antibody against coccidia was first detected. Interferon-secreting cells in the spleen diminished by 80 days after the primary infection. The secretion of interferon by lymphocytes from chickens which are immune to coccidial infection is a useful method of measuring T-cell immunity and a sensitive way of identifying antigenic epitopes recognised by T-cells. Furthermore interferon may be an important mediator in the expression of immunity to coccidial infection in poultry.