1. Allergy and Asthma:
- Result from inappropriate immune responses to common antigens such as pollen, food, or animal dander.
- Charles Richet's discovery of anaphylaxis in 1902 highlighted the adverse effects of immune hypersensitivity.
- Most allergic reactions involve IgE antibodies, leading to symptoms like sneezing, wheezing, difficulty breathing (asthma), dermatitis (hives), and in severe cases, airway blockage.
2. Graft Rejection and Graft-versus-Host Disease (GVHD):
- Transplantation of foreign cells or organs triggers immune responses, leading to rejection.
- Immune system recognizes transplants as foreign and attacks them.
- GVHD occurs when transplanted cells view the host as nonself, leading to potentially fatal reactions.
- Suppression of immune response via drugs is necessary for transplantation, but it renders the host susceptible to infections.
3. Autoimmune Disease:
- Immune system malfunctions by attacking the body's own tissues.
- Loss of self/nonself discrimination leads to chronic debilitating diseases.
- Examples include:
- Multiple sclerosis: Autoimmune attack on the brain and central nervous system.
- Crohn's disease: Attack on tissues in the gut.
- Rheumatoid arthritis: Attack on joints of the arms and legs.
- Genetic and environmental factors contribute to the onset and progression of autoimmune diseases.
4. Immunodeficiency:
- Results from defects in innate or adaptive immune responses.
- Can be genetic or acquired due to damage by chemical, physical, or biological agents.
- Severity varies depending on the extent of immune dysfunction.
- Predisposes individuals to recurrent infections and increased susceptibility to pathogens.
Clinical Significance:
- Allergy and asthma are among the most common reasons for medical visits, necessitating significant healthcare resources.
- Transplantation is a life-saving treatment option for many, but immune rejection poses a significant challenge.
- Autoimmune diseases cause chronic morbidity and are the focus of extensive research for improved therapies.
- Immunodeficiency increases the risk of infections and requires management to bolster immune function.
Historical Significance:
- Landsteiner's discovery of human blood groups facilitated safe blood transfusions.
- Identification of the major histocompatibility complex (MHC) by Snell, Dausset, and Benacerraf paved the way for understanding transplant immunology.
- Nobel Prizes awarded to Thomas and Murray recognized advancements in transplantation immunity.
Challenges and Future Directions:
- Developing strategies to prevent immune rejection while maintaining overall immune function remains a significant challenge in transplantation medicine.
- Understanding the complex interplay of genetic and environmental factors in autoimmune diseases is crucial for developing targeted therapies.
- Research in immunodeficiency aims to uncover underlying mechanisms and develop personalized treatments.