Multisystem inflammatory syndrome in children – allergist and immunologist point of view

Multisystem inflammatory syndrome in children associated with COVID-19 (MIS-C) is a complication following SARS-CoV-2 infection. It may appear a few weeks after coronavirus infection, even if it was asymptomatic. Symptoms may appear gradually in the following days of illness and may be mild to severe in its course. The most common symptoms of MIS-C include fever > 3 days, gastrointestinal symptoms, skin changes. Shock can often occur. The key pathomechanism of the syndrome is hyperinflammation and an altered cytokine profile. Activation of T lymphocytes in MIS-C is mediated by the superantigen, which is the spike protein of the virus. The clinical picture and the immune pathophysiological profile show similarities between MIS-C and Kawasaki diseases (KD). The relationship of MIS-C with allergic diseases has not been investigated, but by analogy it can be assumed that it will be similar to KD. Allergic rhinitis, asthma, and atopic dermatitis have been demonstrated to increase following KD. Children who have previously suffered from combined allergic diseases (atopic dermatitis, allergic rhinitis, and urticaria) are at an increased risk of developing KD. There is an increased risk of KD in children who had sought medical care for allergic diseases more than twice a year compared to children with fewer medical visits. Data on the relationship of KD with atopy indicate the need to undertake studies analyzing MIS-C in this context.