Neopterin production and tryptophan degradation in humans infected by Streptococcus pyogenes.
Streptococcus pyogenes may cause tonsillitis, scarlet fever and so-called "streptococcal toxic shock-like syndrome" (STSS). These streptococci produce exotoxins which are implicated as superantigens in the pathogenesis of STSS and scarlet fever. Using human peripheral blood-derived mononuclear cells in vitro, such toxins were shown to induce neopterin production and degradation of the amino acid tryptophan to metabolites such as kynurenine by activating indoleamine (2,3)-dioxygenase via interferon-gamma. We investigated the sera of seven patients with streptococcal tonsillitis and of four patients with STSS. Those with STSS showed higher serum neopterin concentrations (median: 152 nmol/l; 95th percentile in healthy controls: 8.7 nmol/l) than those with tonsillitis (median: 12 nmol/l). Similarly, kynurenine to tryptophan ratios were increased in tonsillitis and extremely high in patients with STSS. Highly increased neopterin production and tryptophan degradation in patients with STSS suggest an association between a high degree of T cell activation and the severity of the disease manifestation.
Murr
C
C
Institute for Medical Chemistry and Biochemistry, University of Innsbruck, Austria.
Gerlach
D
D
Widner
B
B
Dierich
M P
MP
Fuchs
D
D
D006801:Humans; D007737:Kynurenine / Q000378:metabolism; D019798:Neopterin / Q000096:biosynthesis*; D013290:Streptococcal Infections / Q000378:metabolism*; D013297:Streptococcus pyogenes / Q000378:metabolism*; D014069:Tonsillitis / Q000097:blood; D014364:Tryptophan / Q000378:metabolism*
D007737:Kynurenine; D019798:Neopterin; D014364:Tryptophan