As a model system for mucocutaneous lymph node syndrome (MCLS), we have advocated and used mice which had been rendered tolerant to Streptococcus pyogenes‐associated antigens by neonatal infection with group A fteta‐hemolytic streptococci, because these mice have shown a variety of peculiar bioimmunological characteristics bearing a striking resemblance to those of MCLS patients. The results of our current investigations reaffirmed the reliability of the animal model by indicating that mice subjected to neonatal infection with 5. pyogenes, or inoculation with streptococcal pyrogenic exotoxin (SPE) in Freund's adjuvant, were perfect counterparts of patients with MCLS on account of their platelet activation and hyperaggregability in response to provocative treatment, which are familiar findings in this disease.

We report on a patient with severe serum sickness induced by carbamazepine in whom anticarbamazepine IgG antibodies were detected in the serum. The T cells of the patient showed impairment of phytohemagglutinin-induced proliferation, and hypergammaglobulinemia was evident. The clinical features and immunological abnormalities were compatible with immunoblastic lymphadenopathy. Immunosuppressive factors were also detected in the patient. Their molecular weights ranged from 20,000 to 30,000 as evaluated by Sephadex G-200 gel filtration. Such immunosuppressive cytokines were not detected in other patients with carbamazepine allergy who did not develop the clinical manifestations of immunoblastic lymphadenopathy. These results suggest that the T cell functional deficiency of immunoblastic lymphadenopathy is induced by these immunosuppressive cytokines.

Mice made tolerant to streptococcal pyrogenic exotoxin (SPE) by neonatal inoculation with SPE emulsified in incomplete Freund's adjuvant demonstrated early thrombocytopenia followed by thrombocytosis. This state is the perfect counterpart of patients with mucocutaneous lymph node syndrome (MCLS). We have hypothesized that by inducing tolerance to SPE, the biological activities of the toxin might play leading roles in the pathogenesis of MCLS. In the present investigations, the efficacy of SPE on the prophylaxis and treatment of diseases caused by Streptococcus pyogenes (including MCLS) were monitored using the murine model system accompanied with a platelet‐counting technique. The mice, rendered tolerant due to neonatal SPE inoculation and followed by immunization with SPE toxoid about 1 month prior to the provocative injections with SPE, demonstrated an almost complete lack of response to the provocation, keeping platelet counts within the normal range of values (except for a marginally significant thrombocytosis 7 days postprovocation). Moreover, anti‐SPE titers of the sera from the mice sacrificed on day 35, at which point the observation was terminated, were proved to be markedly elevated when compared with controls. These findings seem to suggest that immunization with the toxoid could overcome tolerance, resulting in the production of an antitoxin. In a second experiment that examined the effect of administration with rabbit antiserum raised against the toxoid, the antiserum‐treated mice demonstrated a transitory thrombocytosis on 7 days postprovocation with SPE, followed by an abrupt decrease in the number of platelets from day 10 onward. Such a finding was in complete agreement with that observed in tolerant mice administered with antiserum specific for SPE, suggesting a strong neutralizing activity against SPE of the antitoxoid serum. A third experiment evaluated the effect of F(ab')2 fragments of the rabbit antiserum to the toxoid on platelet activity. The tolerant mice passively administered i.v. with the F(ab')2 fractions demonstrated a complete lack of responsiveness, except for a small thrombocytosis on days 7 and 10.

An anticarbamazepine antibody was detected in the serum of a patient with severe carbamazepine-induced serum sickness. We found that the patient's T cells and IgG antibody recognized an epitope which appeared in subjects showing an allergic reaction, as well as that in subjects who showed no allergic reaction, after long-term carbamazepine therapy. These results show that an anti-carbamazepine immune response does not occur in the majority of subjects who undergo long-term carbamazepine therapy without developing allergic symptoms, although the immunodominant haptenic epitope of carbamazepine is present in their sera.

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