The whole-blood gamma interferon (IFN-γ) ELISA is a useful test for diagnosis of Mycobacterium avium subsp. paratuberculosis infection in cattle, but becomes less effective late in the disease due to the unresponsiveness of the infected animals. The present study demonstrated that the suppressive effect of interleukin-10 (IL-10) is involved in the unresponsiveness. Monoclonal antibody (MAb) neutralization of IL-10 increased whole-blood IFN-γ secretion in infected animals 23-fold following stimulation with Johnin purified protein derivative (PPD). The MAb did not change the PPD-induced IFN-γ level in uninfected animals. The amplification of the whole-blood PPD-induced IFN-γ response by the IL-10-neutralizing MAb can help improve diagnosis of the disease, particularly in the subclinical stage, for animals having an IFN-γ response below the detection limit in the IFN-γ ELISA.
(Paratuberculosis and Inflammatory Bowel Disease Research Team, Department of Planning and Coordination TEL +81-29-838-7781)
References:
1. Buza et al. (2003) Infect. Immun. 71:7223-7227.
2. Buza et al. (2004) Infect. Immun. 72:2425-2428.
