Tuberculin skin test reactivity in Kawasaki disease

A strongly positive tuberculin skin reaction (> 1.5 cm2) was observed during the acute phase of the illness in 11 children with Kawasaki disease (KD), but not in control pediatric patients with other febrile infections (41 patients) or diseases similar to KD (9 patients). The cutaneous sensitivity to intermediate strength [5 tuberculin units (TU)] purified protein derivative (PPD) inoculation had completely disappeared by the second monthly checkup. Peripheral blood T lymphocytes from KD subjects proliferated vigorously and produced significant amounts of IL-2 in response to the stimulation elicited by 0.05 TU/mL of PPD. In contrast, the proliferative response of, and IL-2 release by, control T cells was within background values. Mounting laboratory evidence suggests that heat shock proteins (HSP) may be involved in the pathogenesis of KD. Our clinical and experimental data may, therefore, have been due to immunologic cross-reactivity between mycobacterial derived HSP65 and its human homologue HPS63 (self P1 antigen). Despite the low number of patients investigated, our findings suggest that the tuberculin skin test and its in vitro correlates (T cell mitogenesis and IL-2 production) could provide simple and reliable diagnostic tools for identifying atypical forms of KD, or vice versa, in subjects not vaccinated against tuberculosis.