Mechanisms of Hypersensitivity Reactions

Introduction

Hypersensitivity reactions are exaggerated immune responses to an antigen, leading to tissue damage and inflammatory effects. Understanding the mechanisms behind these reactions is crucial for effective management and therapeutic intervention.

Classification of Hypersensitivity Reactions

Type I - Immediate Hypersensitivity

Type I reactions are IgE-mediated and occur within minutes of antigen exposure. Common manifestations include anaphylaxis, allergic rhinitis, and asthma.

Type II - Cytotoxic Hypersensitivity

Type II reactions involve antibody-mediated destruction of cells, seen in conditions such as hemolytic anemia and Goodpasture’s syndrome.

Type III - Immune Complex-Mediated Hypersensitivity

Characterized by the deposition of immune complexes, leading to tissue inflammation as seen in systemic lupus erythematosus (SLE) and serum sickness.

Type IV - Delayed-Type Hypersensitivity

Cell-mediated responses that take 24-72 hours to develop, commonly observed in tuberculosis and contact dermatitis.

Therapeutic Approaches and Management Strategies

• Pharmacological Intervention: Antihistamines, corticosteroids, and monoclonal antibodies targeting immune mediators.
• Allergen Avoidance: Reducing exposure to known triggers to minimize hypersensitivity reactions.
• Immunotherapy: Allergy shots and desensitization techniques to modify immune response.
• Emergency Management: Epinephrine administration for anaphylactic reactions.

Conclusion

Understanding hypersensitivity mechanisms allows clinicians to develop targeted therapeutic strategies for effective patient care. Continued research and advanced treatment modalities are essential for improving outcomes in hypersensitivity-related disorders.