A 24-year-old patient complains about general weakness, dizziness, body temperature rise up to 37,5°C, sore throat, neck edema, enlargement of submaxillary lymph nodes. Objectively: mucous membrane of oropharynx is edematic and cyanotic, tonsils are enlarged and covered with films that spread beyond the tonsils and cannot be easily removed. What is the leading mechanism of this illness' development?