Circulating immune complex in the mucocutaneous lymph node syndrome.

In 16 patients with mucocutaneous lymph node syndrome (MCLS) during the first 2 weeks after the onset (acute phase) and 1 month after the onset (remission phase), measurement of the circulating immune complex (CIC) was performed by a C1q-binding assay (C1q-B.A.) and/or a Protein-A precipitation test (protein-A P.T.). Seven out of 12 samples and four out of nine samples were shown to have raised levels of CIC in the acute phase with the C1q-B.A. and Protein-A P.T. test. In the remission phase, on the other hand, positive results were found in one out of six samples with the C1q-B.A. test and in three out of nine samples with the Protein-A P.T. test. High levels of CIC and disease activity were parallel. Our finding of a higher incidence of positive CIC in MCLS supports the possibility of the immunopathological mechanism.