Relationship between the production of interferon-α/β and interferon-γ during acute toxoplasmosis

Abstract

SUMMARY: Acute toxoplasmosis was induced in mice, and interferon (IFN) production in serum and by spleen cells was evaluated during the infection period. Interferon was characterized by acid-treatment and anti-IFN-α/β neutralization. In order to verify the correlation between the unusual aspects of the IFN production and the induction of immunosuppression, splenocyte mitogen responsiveness was investigated concomitantly to IFN synthesis. The activity ofToxoplasma-induced serum IFN-α/β increased gradually throughout all post-infection days, but IFN-γ was not detected in the systemic circulation at any time during the infection. It was also observed that IFN-α/β production and the capacity to produce IFN-γ by spleen cells were closely and inversely correlated. As the infection progressed, more IFN-α/β was produced, and the ability of spleen cells to produce IFN-γ decreased. The observation thatToxoplasma-infected mice were concomitantly immunosuppressed (as documented by mitogen unresponsiveness and defective IFN-γ production) in direct correlation to IFN-α/β production, suggests that such IFN-α/β production is an important factor associated with acute toxoplasmosis-induced immunosuppression.