Kawasaki Disease: Laboratory Findings and an Immunopathogenesis on the Premise of a ""Protein Homeostasis System

Lee, Kyung-Yil; Rhim, Jung-Woo; Kang, Jin-Han

KD has an age predilection for children from 6 months of age to 5 years of age, with a peak incidence in children between 6 and 24 months old. This trait has not changed since the emergence of KD and is reflected in all ethnic groups. This disposition suggests that the maturing immune system in early childhood is involved in the pathogenesis of KD. 13 In general, acute infectious diseases affect children of all ages, although the phenotypes of some infectious diseases are age-dependent. In viral infections such as hepatitis A virus, coronavirus (SARS) and influenza virus as well as in mycoplasma infections, younger children (<5 years of age) show less severe clinical symptoms and signs, compared to older children (>5 years of age) and adults. [26] [27] [28] [29] On the contrary, in bacterial infections such as staphylococcal pneumonia and tuberculosis as well as in parasitic infections such as malaria, younger children have a more severe clinical course. 30, 31 In KD, older children had prolonged fever and a higher incidence of CALs compared to younger children. 32, 33 In addition, there are early childhood immune-mediated hematologic disorders, showing a similar age restriction as that of KD, including transient erythroblastopenia of childhood, autoimmune neutropenia of infancy, childhood immune thrombocytopenic purpura, and transient hypogammaglobulinemia of infancy. These disorders may be associated with infectious insults and have a self-limited clinical nature improving before 5 years of age. These findings suggest that the age of around 5 years old in childhood is the turning point of immune maturation of the host. KD may be regarded as among these disease categories, reflecting immunologic immaturity during early childhood, although KD has an acute immune disturbance.