Elevated L-kynurenine level and its normalization by prednisolone in a patient with eosinophilia-myalgia syndrome.
We report a L-tryptophan-induced case of eosinophilia-myalgia syndrome in a Japanese woman and describe the time course of changes in tryptophan metabolism observed during steroid therapy. She had taken 1.0 g of the implicated L-tryptophan daily. When admitted due to painful swelling of her extremities, eosinophil count was 22.3 x 10(9)/L. Before prednisolone treatment, her serum L-kynurenine level was 10.2 mumol/L, a level about three-fold higher than the normal value, while serum tryptophan level was abnormally low (23.1 mumol/L). On the 14th day of prednisolone treatment (40 mg daily), L-kynurenine was declined to 8.1 mumol/L and, concomitantly, L-tryptophan level increased to the normal range (51.0 mumol/L). Subsequently, on the 42nd day of therapy, serum L-kynurenine was normalized. In contrast, serum serotonin level was unchanged throughout the course of this therapy. Prednisolone dramatically reduced the elevated serum L-kynurenine with a reciprocal increase in serum L-tryptophan indicates that abnormal tryptophan metabolism, may play a role in the pathogenesis of eosinophilia myalgia syndrome, and that the observed effect of steroid treatment was due to suppression of elevated activity of indoleamine 2, 3-dioxygenase, a first rate-limiting enzyme of the kynurenine pathway.
Hisatomi
A
A
Third Department of Internal Medicine, Faculty of Medicine, Kyushu University, Japan.
Kubota
A
A
Ohashi
M
M
Umeda
F
F
Nawata
H
H
Imamura
T
T
Nagata
T
T
D000893:Anti-Inflammatory Agents / Q000627:therapeutic use*; D016603:Eosinophilia-Myalgia Syndrome / Q000097:blood / Q000139:chemically induced / Q000188:drug therapy*; D005260:Female; D006801:Humans; D007737:Kynurenine / Q000097:blood*; D008875:Middle Aged; D011239:Prednisolone / Q000627:therapeutic use*; D014364:Tryptophan / Q000009:adverse effects*; D014366:Tryptophan Oxygenase / Q000378:metabolism
D000893:Anti-Inflammatory Agents; D007737:Kynurenine; D014364:Tryptophan; D011239:Prednisolone; D014366:Tryptophan Oxygenase