Immunologic Disorders and Autoimmune Conditions

Comprehensive vocabulary flashcards covering the pathophysiology, clinical manifestations, diagnostic criteria, and management of immunologic disorders, hypersensitivities, autoimmune conditions, and transplant rejections.

Immunology

The branch of science dealing with the physical, chemical, and physiological characteristics of the components of the immune system.

Immune System

A complex network consisting of specialized cells and structures that protect the body against invasion by harmful substances, defends against infection, maintains homeostasis by removing old cells (primarily via the spleen), and identifies and destroys mutant cells.

Lymph Nodes

Specialized lymphoid organs whose primary function is to filter bacteria and foreign cells from the lymph.

Thymus

A primary lymphoid organ responsible for the production and maturation of T-cells.

Spleen

An abdominal lymphoid organ that filters blood, produces lymphocytes and monocytes, destroys bacteria, and primarily removes old, worn-out cells to maintain homeostasis.

Bone Marrow

The primary site of hematopoiesis that serves as the source of lymphocytes and macrophages, removes old cells, and contains stem cells that evolve into B-cells, T-cells, and phagocytes.

Innate Immunity (Natural Immunity)

A non-specific defense mechanism that does not create immunologic memory and is built into the body from birth, consisting of surface barriers, secretions, phagocytosis, natural killer (NK) cells, inflammation, fever, and antimicrobial proteins.

Interferon

An antimicrobial protein released by virus-infected cells that acts on neighboring uninfected cells to degrade RNA, inhibit protein synthesis, promote apoptosis of infected cells, and activate immune cells.

Complement System

A biochemical cascade of proteins that enhances the immune response and inflammation while opsonizing pathogens to facilitate clearance by phagocytes.

Acquired Immunity (Adaptive Immunity)

A specific defense mechanism that develops memory by recognizing foreign antigens and producing targeted antibodies and effector T cells to neutralize and destroy them.

Antibody-Mediated Immunity (Humoral Immunity)

An adaptive immune defense wherein antibodies (immunoglobulins) produced by B-cells in the spleen and lymph nodes circulate in blood and lymph to bind antigens and trigger targeted immune responses.

Cell-Mediated Immunity (CMI)

An adaptive immune defense governed by T-cells that differentiate self from non-self, providing surveillance against malignancy, metastasis, and virally infected cells by directly binding antigen-bearing cells.

Multiple Sclerosis (MS)

An immune-mediated, progressive neurodegenerative demyelinating disease of the central nervous system typically presenting in adults aged $20$ to $40\text{ years}$, with a higher prevalence in women.

Demyelination

The inflammatory destruction of the fatty and proteinaceous myelin sheath and oligodendrocytes in the CNS, resulting in interrupted nerve impulse flow, plaque formation, and permanent axonal degeneration.

Oligoclonal Banding

A diagnostic finding visualized on CSF electrophoresis in multiple sclerosis, representing pooled immunoglobulin G ($\text{IgG}$) indicative of an abnormal localized central immune response.

Baclofen (Lioresal)

A gamma-aminobutyric acid ($\text{GABA}$) agonist that serves as the medication of choice for controlling spasticity in patients with multiple sclerosis.

Type 1 Diabetes Mellitus (IDDM)

A chronic autoimmune disease characterized by the immune-mediated destruction of pancreatic beta cells, causing an absolute insulin deficiency, an acute onset usually before $30\text{ years}$ of age, and high susceptibility to ketoacidosis.

Diabetic Ketoacidosis (DKA)

An acute metabolic emergency in type 1 diabetes resulting from absolute insulin deficiency, characterized by blood glucose of $250\text{--}500+\,\text{mg/dL}$, ketonemia, metabolic acidosis ($\text{pH} \le 7.35$), Kussmaul respirations, fruity acetone breath, and abdominal pain.

Microalbuminuria

The earliest clinical and laboratory evidence of diabetic nephropathy detected through sensitive urine protein screening.

Glomerulonephritis

Inflammation of the renal glomerular capillaries and small vessels, often caused by deposition of immune complexes following a Group A beta-hemolytic streptococcal infection ($7\text{--}12\text{ days}$ prior), leading to membrane thickening, decreased GFR, hematuria, and proteinuria.

Plasmapheresis

An extracorporeal medical procedure in which blood is filtered through a plasma separator to eliminate circulating pathologic antibodies and immune complexes from the circulation.

Atopic Disorders

A group of hereditary, $\text{IgE}$-mediated disorders characterized by local exaggerated type I hypersensitivity reactions to common environmental allergens; includes allergic rhinitis, asthma, and atopic dermatitis (eczema).

The Allergic Triangle

The clinical triad consisting of allergic rhinitis, asthma, and eczema, reflecting the phenomenon that an individual with one atopic condition is predisposed to developing the other two.

Anaphylaxis

An acute, systemic, and life-threatening type I hypersensitivity reaction resulting from rapid release of $\text{IgE}$-mediated mediators (histamine, prostaglandins, leukotrienes) from mast cells and basophils, causing bronchospasm, laryngeal edema, and cardiovascular collapse.

Epinephrine (1:1000)

The first-line emergency sympathomimetic medication administered subcutaneously or intramuscularly in a $1:1000$ dilution to treat acute anaphylaxis by reversing bronchospasm, mucosal edema, and hypotension.

Allergic Rhinitis (Hay Fever)

The most common form of respiratory allergy, mediated by an immediate type I hypersensitivity reaction to airborne allergens (pollens, molds) and manifesting as sneezing, watery rhinorrhea, nasal congestion, and sinus pressure.

Rhinitis Medicamentosa

Rebound nasal mucosal congestion and hyperresponsiveness caused by the overuse of topical alpha-adrenoceptor decongestant sprays for longer than $3\text{ to }5\text{ days}$.

Contact Dermatitis

An acute or chronic localized skin inflammation resulting from direct contact with chemicals or allergens, mediated by a type IV delayed cell-mediated hypersensitivity reaction and diagnosed via patch testing (such as the TRUE test).

Atopic Dermatitis

A type I immediate hypersensitivity pruritic skin disorder characterized by cutaneous hyperreactivity, elevated serum $\text{IgE}$, peripheral eosinophilia, dry skin, and secondary excoriated lesions in areas of sweating and hypervascularity.

Dermatitis Medicamentosa

A type I hypersensitivity disorder characterized by sudden-onset, vividly colored drug eruptions on the skin following medication administration, which rapidly resolve upon drug withdrawal.

Angioneurotic Edema

A non-pitting, diffuse edema involving the deep dermis and subcutaneous tissues, commonly affecting the lips, eyelids, cheeks, tongue, and larynx; frequently triggered as an adverse reaction to ACE inhibitors or penicillin.

Hereditary Angioedema

A genetic non-allergic condition presenting with episodic, self-limiting ($1\text{--}4\text{ days}$) diffuse edema of the skin, gastrointestinal tract, and upper airway, presenting a risk of life-threatening laryngeal asphyxiation.

Latex Allergy

An allergy triggered by proteins from the rubber tree (Hevea brasiliensis) or chemicals used in manufacturing, manifesting as type I immediate hypersensitivity (urticaria, asthma, anaphylaxis) or type IV contact dermatitis, with potential cross-reactivity to kiwi, banana, avocado, and chestnut.

Systemic Lupus Erythematosus (SLE)

A chronic, progressive, systemic autoimmune disease characterized by excessive production of antinuclear antibodies (ANAs) against cellular DNA, resulting in circulating immune complexes, vasculitis, and multi-organ damage.

SOAP BRAIN MD

A clinical diagnostic mnemonic for SLE representing: Serositis, Oral ulcers, Arthritis, Photosensitivity, Blood dyscrasias, Renal disorder, ANA positivity, Immunologic abnormalities (anti-dsDNA, anti-Sm), Neurologic disorder, Malar rash, and Discoid rash.

Butterfly Rash (Malar Rash)

A distinctive erythematous, scaly, raised rash across the bridge of the nose and cheeks characteristic of Systemic Lupus Erythematosus, often provoked or worsened by sun exposure.

Rheumatoid Arthritis (RA)

A chronic systemic autoimmune disease of unknown etiology characterized primarily by progressive symmetrical inflammation of synovial joints, leading to cartilage degradation and bony erosion.

Pannus

An abnormal proliferative layer of granulation and synovial tissue rich in inflammatory enzymes and osteoclasts that invades and destroys articular cartilage and erodes bone in rheumatoid arthritis.

Autograft

A tissue or organ transplanted from one area of an individual to another location on the same individual, posing zero risk of graft rejection.

Isograft (Syngeneic Graft)

A graft transplanted between genetically identical (monozygotic) twins, presenting virtually no concern for immunological rejection.

Allograft

A tissue or organ transplanted between genetically non-identical individuals of the same species, requiring immunosuppressive therapy to prevent host T-cell rejection.

Xenograft

A surgical graft transplanted from an animal donor of one species into a recipient of another species (such as animal to human), with high potential for immunologic rejection.

Hyperacute Rejection

A fulminant transplant rejection occurring within minutes to hours after surgery, driven by pre-formed recipient antibodies attacking donor endothelium, necessitating immediate organ removal.

Acute Rejection

A cell-mediated transplant rejection occurring within days to months post-transplantation, caused by host cytotoxic T lymphocytes attacking donor graft tissue; typically reversible with augmented immunosuppressive therapy.

Chronic Rejection

An irreversible, progressive decline in transplanted organ function occurring over months to years due to chronic fibrosis and vascular scarring; can only be resolved by retransplantation.

Graft-versus-Host Disease (GVHD)

A severe immunological complication primarily following allogeneic bone marrow or stem cell transplantation, where mature donor immunocompetent T-cells attack the immunocompromised recipient's tissues, typically presenting with a triad of dermatitis, hepatitis, and enteritis.