Hypersensitivity and Allergy Types

Hypersensitivity

• Type I Hypersensitivity: immediate allergic reactions mediated by IgE antibodies
  • Symptoms: hives, bronchoconstriction, vasodilation, edema
  • Example: person stung by a bee experiencing anaphylactic shock
• Type II Hypersensitivity: cytotoxic reactions where IgG or IgM antibodies target cells for destruction
  • Symptoms: hemolysis, tissue damage
  • Example: patient receiving wrong blood type during transfusion
• Type III Hypersensitivity: immune complex-mediated reactions where antigen-antibody complexes deposit in tissues
  • Symptoms: inflammation, tissue damage
  • Example: post-streptococcal glomerulonephritis causing kidney inflammation
• Type IV Hypersensitivity: delayed-type reactions mediated by T cells
  • Symptoms: localized skin reactions, chronic inflammation
  • Example: tuberculin skin test showing delayed reaction in tuberculosis

Autoimmune Disorders

• Systemic Lupus Erythematosus (SLE): chronic autoimmune disease causing widespread inflammation and tissue damage
  • Symptoms: butterfly rash, joint pain, kidney damage, fatigue
  • Example: young woman presenting with facial rash and joint pain, diagnosed with SLE after positive ANA test
• Rheumatoid Arthritis (RA): autoimmune disorder causing chronic inflammation of the joints
  • Symptoms: joint swelling, pain, stiffness, deformities
  • Example: middle-aged patient with morning stiffness and swollen joints, confirmed as RA via rheumatoid factor and anti-CCP antibodies

Immunodeficiency Disorders

• Severe Combined Immunodeficiency Disease (SCID): genetic disorder causing profound immune system deficiency
  • Symptoms: frequent infections, failure to thrive
  • Example: infant with persistent infections and poor growth, diagnosed with SCID and requiring bone marrow transplant
• Selective IgA Deficiency: most common primary immunodeficiency, marked by low levels of IgA
  • Symptoms: recurrent respiratory and gastrointestinal infections
  • Example: child with recurrent sinus infections and chronic diarrhea, found to have low serum IgA levels
• DiGeorge Syndrome: genetic disorder causing thymic hypoplasia, leading to T-cell deficiency
  • Symptoms: congenital heart defects, hypocalcemia, recurrent infections
  • Example: newborn with cardiac anomalies, facial dysmorphisms, and low T-cell count, diagnosed with DiGeorge syndrome
• HIV Infection: virus that attacks the body's immune system, specifically the CD4+ T cells
  • Symptoms: fever, weight loss, opportunistic infections, Kaposi's sarcoma
  • Example: adult with recurrent infections and weight loss, tested positive for HIV and requires antiretroviral therapy

White Blood Cell Disorders

• Leukopenia: low white blood cell count, increasing infection risk
  • Symptoms: frequent infections, fever, chills
  • Example: patient undergoing chemotherapy presents with recurrent fevers and is diagnosed with leukopenia
• Leukocytosis: high white blood cell count, indicating infection or inflammation
  • Symptoms: fever, swelling, pain
  • Example: patient with appendicitis shows elevated white blood cell count in blood tests
• Acute Lymphoblastic Leukemia (ALL): cancer of the blood and bone marrow that affects white blood cells
  • Symptoms: fatigue, fever, bleeding, bone pain
  • Example: child presenting with fatigue, bruising, and bone pain, diagnosed with ALL after bone marrow biopsy
• Chronic Lymphocytic Leukemia (CLL): slow-growing leukemia affecting lymphocytes
  • Symptoms: enlarged lymph nodes, fatigue, weight loss
  • Example: elderly patient with painless swollen lymph nodes and night sweats, diagnosed with CLL via blood tests showing high lymphocyte count
• Hodgkin's Lymphoma: type of lymphoma characterized by the presence of Reed-Sternberg cells
  • Symptoms: painless lymph node enlargement, night sweats, weight loss
  • Example: young adult with painless neck lump and persistent night sweats, diagnosed with Hodgkin's lymphoma after lymph node biopsy
• Non-Hodgkin's Lymphoma: diverse group of blood cancers affecting lymphocytes
  • Symptoms: swollen lymph nodes, fever, night sweats, weight loss
  • Example: middle-aged patient with unexplained weight loss and fever, found to have non-Hodgkin's lymphoma on imaging and biopsy

Red Blood Cell Disorders

• Anemia: condition where there is a deficiency of red blood cells or hemoglobin
  • Symptoms: fatigue, pallor, shortness of breath, dizziness
  • Example: patient with chronic fatigue and pallor, diagnosed with anemia through low hemoglobin levels
• Anemia of Acute Blood Loss: rapid loss of blood causing a decrease in red blood cell mass
  • Symptoms: hypotension, tachycardia, pallor, fatigue
  • Example: trauma patient with significant blood loss from an injury, showing signs of acute anemia
• Anemia of Chronic Blood Loss: slow, ongoing blood loss leading to anemia
  • Symptoms: fatigue, pallor, dizziness
  • Example: patient with chronic gastrointestinal bleeding from ulcers, resulting in anemia
• Hemolytic Anemia: anemia caused by the destruction of red blood cells
  • Symptoms: jaundice, dark urine, fatigue
  • Example: patient with jaundice and dark urine, diagnosed with hemolytic anemia after blood tests
• Sickle Cell Anemia: genetic disorder causing abnormal hemoglobin, leading to sickle-shaped red blood cells
  • Symptoms: painful crises, anemia, infections
  • Example: child with recurrent painful episodes and anemia, diagnosed with sickle cell disease through genetic testing
• Hemolytic Disease of the Newborn: condition where maternal antibodies attack fetal red blood cells
  • Symptoms: jaundice, anemia, edema
  • Example: newborn with severe jaundice and anemia, diagnosed with hemolytic disease of the newborn after Coombs test
• Iron-Deficiency Anemia: anemia caused by a lack of iron, leading to reduced hemoglobin production
  • Symptoms: fatigue, pallor, pica
  • Example: patient with chronic fatigue and craving for non-food substances, diagnosed with iron-deficiency anemia after iron studies
• Pernicious Anemia: anemia caused by vitamin B12 deficiency due to lack of intrinsic factor
  • Symptoms: fatigue, glossitis, neurological symptoms
  • Example: elderly patient with fatigue and numbness in hands, diagnosed with pernicious anemia after blood tests showing low B12 levels

Platelets, Hemostasis, and Coagulation Disorders

• Thrombocytopenia: low platelet count leading to increased bleeding risk
  • Symptoms: easy bruising, petechiae, excessive bleeding
  • Example: patient with unexplained bruising and low platelet count diagnosed with thrombocytopenia
• Thrombocytosis: high platelet count leading to increased clotting risk
  • Symptoms: headaches, dizziness, chest pain
  • Example: patient with persistent headaches and high platelet count found to have thrombocytosis
• Immune Thrombocytopenic Purpura (ITP): autoimmune disorder causing platelet destruction
  • Symptoms: bruising, petechiae, nosebleeds
  • Example: child with sudden onset of bruising and petechiae, diagnosed with ITP
• Hemophilia: genetic disorder causing deficient clotting factors
  • Symptoms: prolonged bleeding, hemarthrosis
  • Example: young boy with excessive bleeding after minor injuries, diagnosed with hemophilia
• Hemolytic-Uremic Syndrome (HUS): condition causing hemolysis and kidney failure, often triggered by infection
  • Symptoms: bloody diarrhea, hematuria, renal failure
  • Example: child presenting with bloody diarrhea and renal failure after E. coli infection, diagnosed with HUS

Arterial Disorders

• Hyperlipidemia: elevated levels of lipids in the blood, increasing atherosclerosis risk
  • Symptoms: often asymptomatic, detected via blood tests
  • Example: patient with high cholesterol levels identified during routine blood screening
• Hypertension: chronic high blood pressure leading to cardiovascular damage
  • Symptoms: often asymptomatic, can cause headaches, vision problems
  • Example: patient with consistent blood pressure readings above 140/90 mmHg, diagnosed with hypertension
• Atherosclerosis: buildup of plaque in the arterial walls leading to reduced blood flow
  • Symptoms: chest pain, leg pain, shortness of breath
  • Example: patient with chest pain during exertion, diagnosed with coronary artery disease due to atherosclerosis
• Aneurysm: abnormal dilation of a blood vessel, risking rupture
  • Symptoms: often asymptomatic, detected via imaging
  • Example: patient with sudden severe headache, found to have a cerebral aneurysm on a CT scan
• Kawasaki Disease: acute childhood illness causing inflammation of blood vessels
  • Symptoms: fever, rash, swollen hands and feet
  • Example: child with prolonged fever and red eyes, diagnosed with Kawasaki disease after clinical examination

Ischemic Heart Disease and Conduction Disorders

• Acute Coronary Syndrome (ACS): spectrum of conditions caused by reduced blood flow to the heart
  • Symptoms: chest pain, shortness

Identify and understand the different types of hypersensitivity reactions, including immediate allergic reactions and cytotoxic reactions. Learn about the symptoms and examples of each type.