Patho Chapter 12

Nonspecific response

inflammation, phagocytosis, some antimicrobial proteins

Specific response

Production of specific antibodies against foreign substances

Humoral immunity

antibodies are produced to protect body

Cell-mediated immunity

specific lymphocytes are activated to attack nonself cells to protect the body

Helper T cell

Produces phagocytic T and B cells

Cytokine

Stimulates cytotoxic T cells responsible for attacking and killing pathogens

Antigens

Substance that can trigger immune response in body

Self antigen

HLA proteins label cells of the individual; immune system ignores these cells

Non-self antigens

Immune system recognizes these as foreign; development of a specific response to that particular antigen; memory cells produced to quickly respond to the antigen

Antibodies

Produced by plasma cells to identify and neutralize foreign antigens (immunoglobulins); bind to antigens

Neutralization

Directly blocks the antigen; binds to the membrane of the pathogen

Opsonization

Mark the pathogen for removal by macrophages

Complement activation

Bind to proteins of the complement system, which helps to destroy foreign cells by punching holes in their membranes

IgG

Most common in blood, produced during the secondary immune response

IgM

First to increase, produced during the primary immune response

IgA

Common in secretions (tears, saliva, breast milk)

IgE

Responsible for allergic response, results in inflammation

IgD

Binds to activate B cells

Major histocompatibility complex

Set of molecules displayed on cell surfaces; aka human leukocyte antigen; each person has a unique set

MHC type I

Mostly “self”; receptors recognized by CD8 (T - cytotoxic)

MHC type II

Receptors recognized by CD4 (T - helper)

Graft

Cell, tissue, or organ transplanted to replace damaged tissue

Allograft

The donor and recipient are related or unrelated but share similar HLA types; allogenic

Syngeneic graft

The donor and recipient are identical twins; they share the same HLA type

Autograft

The donor and recipient are the same person; autologous

Transplant rejection

Recipient's immune system attacks a transplanted organ or tissue due to differences in their genetic markers (HLA)

Hyperacute rejection

Transplant rejection that occurs almost immediately after transplantation, antibody mediated

Acute rejection

Transplant rejection that occurs within first few months after transplantation with signs of organ failure; may occur months or years after immunosuppression has been terminated

Chronic rejection

Transplant rejection where after prolonged period, immune mediated inflammatory graft injury; mechanism is unclear

Graft-versus-host-disease

Occurs after allogenic transplants when graft (transplant) cells recognize recipient’s antigens as foreign; occur when immune competent donor cells transplanted into immune compromised recipients

Hypersensitivity type I

Immediate hypersensitivity—allergic reactions rapid immune reaction that occurs within minutes of re-exposure to a specific antigen (allergen); skin rashes, hay fever; can be local/atopic or systemic

Primary phase of hypersensitivity type I

Vasodilation, vascular leakage, smooth muscle contraction

Secondary phase of hypersensitivity type II

More intense infiltration of tissues with eosinophils and other acute and chronic inflammatory cells; tissue destruction in the form of epithelial cell damage

Urticaria

hives, atopic dermatitis

Anaphylaxis

Severe, systemic Type I, hypersensitivity reaction life-threatening causes systemic response to the inflammatory mediators

Vasodilation

Histamine, kinins, and prostaglandins all cause _______ in anaphylaxis

Bronchoconstriction 

Acetylcholine, kinins, leukotrienes can cause _________ in anaphylaxis, which leads to airway obstruction

Type II cytotoxic hypersensitivity

Antigen is usually present on cell membrane, may be normal body component or exogenous; circulating IgMs and IgGs react with antigen: destruction by phagocytosis or cytolytic enzymes; Antibodies act as a “tag” and bind surface antigens activates the complement system, proteins that cause the cell to lyse and die

Myasthenia gravis

Antibodies attack acetylcholine receptors; disease caused by type II hypersensitivity 

Graves’ disease

Antibodies stimulate TSH receptors; disease caused by type II hypersensitivity

Type III immune complex hypersensitivity

Mediated by the formation of insoluble antigen– antibody complexes that activate the complement pathway; responsible for the vasculitis seen in certain autoimmune diseases

Type IV cell-mediated hypersensitivity 

Delayed response by sensitized T lymphocytes; first exposure activates T-cells, second exposure T-helper cells release cytokines

Autoantibodies

Antibodies against self antigens

Loss of self tolerance

Development of antibodies against own cells or tissues

Women

Autoimmune disorders are more common in ________; sex difference

Familial

Autoimmune disorder genetic predisposition; certain HLA types are more often linked to autoimmune diseases

Systemic

SLE, rheumatic fever, rheumatoid arthritis, systemic sclerosis, polyarteritis nodosa

Limited to a single organ

Multiple sclerosis: CNS, Hashimoto’s thyroiditis, Graves’ disease: thyroid, Autoimmune hemolytic anemia: blood, Pemphigus vulgaris: skin, Myasthenia gravis: muscle

Systemic Lupus Erythematosus

Formation of immune complexes deposited into tissues cause inflammation and necrosis; manifestations - facial rash/”butterfly rash”, arthralgia/joint pain, and cardiovascular problems

serum antibodies and LE cells

Diagnostic tests for Systemic Lupus Erythematosus (SLE)

Immunodeficiency 

Partial or total loss of one or more immune system components. Increase the risk of infection and cancer

Primary deficiency

Basic developmental failure somewhere in the system

Secondary or acquired immunodeficiencies

Loss of the immune response from specific causes - Infections, splenectomy, malnutrition, immunosuppressant drugs, radiation, chemotherapy (cancer)

Acquired Immunodeficiency Syndrome

Chronic infectious disease caused by the human immunodeficiency virus (HIV); increased susceptibility to opportunistic diseases; prolonged latent period 

HIV-positive

Virus is known to be in the body, but no evidence of immunosuppression

AIDS

Marked clinical symptoms with multiple complications (e.g. cancers)

Retrovirus

Contains reverse transcriptase; two types (HIV-1 & HIV-2)

HIV-1

Major cause of AIDS in US and Europe

HIV-2

Major cause of AIDS in central Africa

Reverse transcriptase

An enzyme that takes viral RNA and converts it to DNA

Encephalopathy

Direct infection of brain cells by HIV; sometimes called AIDS dementia

Kaposi sarcoma

A rare type of cancer that develops in the lining of blood vessels and lymph nodes