Possible role of Streptococcus pyogenes in mucocutaneous lymph node syndrome. IX. Quantitation by ELISA of streptococcal pyrogenic exotoxin in the serum of MCLS patients.

In the present paper we describe the use of an enzyme-linked immunosorbent assay reinforced with an introduction of monoclonal antibody, for the detection and quantitation of streptococcal pyrogenic exotoxin (SPE) in the serum of patients with mucocutaneous lymph node syndrome (MCLS). The amount of SPE was usually at a high level, and its 100% incidence in patients' sera was proved whenever the assay was made on the day of admission, thereby showing a marked contrast to carefully matched control sera which failed to mediate any positive result. As for the change in detected amount of the toxin, a clear dichotomy was observed between the serum of gammaglobulin-treated patients and that of infants given aspirin; in the former the positive result turned to negative rapidly following the initiation of treatment coupled with a defervescence, while in the latter the reduction of SPE levels was scarcely monitored for as long as 17 days after the onset of illness. Quantitation of SPE might be an auxiliary test for the diagnosis of MCLS, because a considerable amount of SPE was assessed in a patient who developed characteristic huge coronary artery aneurysms following an illness which did not fulfill the diagnostic criteria. These findings support our speculation in relation to the certain role of S. pyogenes as an etiological agent for MCLS. The possible mechanisms of gammaglobulin treatment in reducing the prevalence of cardiovascular lesions and the duration of systemic inflammation are discussed.