IMMUNOLOGICAL BASIS AND CLINICAL SPECTRUM OF HYPERSENSITIVITY REACTIONS: A SYSTEMATIC REVIEW

Dhanashree R. Patil*, Nikhita H. Bhosale, Sakshi M. Jakate, Supriya B. Sabale

ABSTRACT

Hypersensitivity reactions represent exaggerated or inappropriate immune responses that result in tissue injury, chronic inflammation, or systemic complications. While the immune system primarily serves a protective role, these reactions reflect a pathological deviation where immune mechanisms themselves become harmful. Traditionally classified under the Gell and Coombs system into five types (I–V), hypersensitivity encompasses both antibody-mediated (Types I–III) and T-cell–mediated (Type IV) responses, with Type V describing stimulatory antibody activity as observed in Graves’ disease. This review comprehensively explores the immunological basis, clinical manifestations, diagnostic modalities, and therapeutic interventions associated with hypersensitivity disorders. We analyse the molecular and cellular pathways underlying each type from IgE-mediated anaphylaxis to delayed-type hypersensitivity and correlate them with representative clinical entities such as autoimmune haemolytic anaemia, serum sickness, and Stevens–Johnson syndrome. Diagnostic advancements including allergen specific IgE testing, skin prick and patch assays, are critically evaluated for their precision and clinical applicability. Therapeutic strategies encompassing antihistamines, corticosteroids, epinephrine, monoclonal antibodies, and desensitization protocols are discussed with an emphasis on individualized treatment approaches. Despite significant progress, major knowledge gaps persist in predicting susceptibility and managing atypical or mixed-pattern immune responses. By delineating mechanistic distinctions among hypersensitivity types, this review underscores their diagnostic and therapeutic relevance, advocating for precision immunology and personalized care. Understanding these complex immune pathways not only enhances clinical decision-making but also paves the way for safer, targeted immunomodulatory therapies in hypersensitivity and related immune-mediated disorders.

Keywords: Hypersensitivity, immune reaction, immune-complex and reaction autoimmune reaction, drug allergy, immediate response, delayed response.