Relationship of interferon-gamma and neopterin levels during stimulation with alloantigens in vivo and in vitro

The authors have recently shown that interferon-gamma is capable of activating the key enzyme of pterin biosynthesis in macrophages. This leads to excretion of the stable degradation product neopterin. In this article they present experimental evidence suggesting that stimulation of T cells by alloantigens is associated with release of interferon-gamma-which, in the case of rejection, is locally restricted and not always detectable in the bloodstream. Neopterin induced by this lymphokine, however, readily penetrates tissue barriers and is detectable in the serum.