Complement and protease inhibitors in the mucocutaneous lymph node syndrome.

Total hemolytic activity of serum (CH50), complement components C3 and C4, alpha 1antitrypsin (alpha 1AT), alpha 1antichymotrypsin (alpha 1X), antithrombin III (AT III), alpha 2 macroglobulin (alpha 2M), and inter-alpha-inhibitor (I-alpha-I) were measured in 23 Japanese and 19 European children with the Mucocutaneous Lymph node Syndrome (MCLS) during the acute phase of disease. Second sera, obtained after day 20 were available from 18 Japanese and 10 European children. In 28 out of 31 children with mild disease, as assessed by the coronary risk score of Asai and Kusakawa, complement was normal or elevated during the acute phase. In 10 out of 11 children with high risk scores, CH50 was below the normal range. One child in this group had ECG changes during the acute phase, one patient died and two others developed coronary aneurysms. C1I was elevated in all 42 cases, alpha 1AT in 40, and alpha 1X in 38 patients. alpha 1AT was depressed in two children, one of whom developed an aneurysm. One of the four children with depression of alpha 1X died of myocardial infarction. Decreased concentrations of AT III, alpha 2M and I-alpha-I were frequent and tended to mark the more severe courses of the disease. A third group of 20 children was evaluated 5 weeks to 6 months after the acute illness. Mean concentrations of all five protease inhibitors were completely normalized in this group. The results of this study indicate that consumption of complement and of protease inhibitors occurs in many cases of MCLS during the acute phase. Determination of CH50 appears to be useful to identify high risk patients early in the course of their illness. Transient deficiency of substances for control of inflammation may in part be responsible for the severe vascular lesions seen in some patients.