chp 12

primary vs secondary immunodeficiency

Primary: congenital (present at birth) or inherited

o Humoral (B-cell deficiencies)

o Cellular (T-cell deficiencies)

o Severe combined immunodeficiency (SCID)

Secondary: acquired later in life

Malnutrition

o Infection (HIV infection/AIDS)

o Neoplastic disease (e.g., lymphoma)

o Immunosuppressive therapy (e.g., corticosteroids or transplant rejection

medications)

stem cell transplantation

Allogeneic stem cell transplantation may provide long- term control or a cure for selected primary immunodeficiency disorders

Conditioning Therapy

o Chemotherapy, with or without radiation, suppresses abnormal or diseased bone marrow cells

Stem Cell Infusion

o Healthy donor stem cells are infused intravenously

Hematopoietic Recovery

o The stem cells repopulate the bone marrow and restore blood-cell production

hypersensitivity disorders

Type	Primary mechanism	Typical timing	Example
I	IgE and mast cells	Immediate	Anaphylaxis
II	IgG or IgM against cell or tissue antigens	Hours to days	Transfusion reaction
III	Immune-complex deposition	Hours to days	Serum sickness
IV	T-cell-mediated inflammation	Delayed	Contact dermatitis

type I hypersensitvity

An IgE-mediated response that develops rapidly after allergen exposure

oAntigen may be insect bite, food, etc.

The allergen activates IgE-sensitized mast cells

Mast cells release inflammatory mediators

Mediators cause vasodilation, edema, mucus production, and bronchoconstriction

Reactions remain local or become systemic

Primary or Initial-Phase Response

oDevelops within minutes

oMast cells release stored mediators

oBlood vessels dilate

oVascular permeability increases

oBronchial smooth muscle constricts

Secondary or Late-phase Response

oDevelops hours later

oInflammatory cells enter the tissue

oEdema and mucus production may persist

oBronchospasm and tissue inflammation may worsen

Local allergic reactions

oAllergic rhinitis: Sneezing, itching, watery nasal drainage

oUrticaria: Raised, itchy wheals

oAtopic dermatitis: Itchy, inflamed skin

oAsthma: Airway inflammation and bronchoconstriction

Systemic allergic reaction

Anaphylaxis

Airway swelling

Wheezing

Hypotension

Possible cardiovascular collapse

anaphylaxis

A rapid, systemic Type I hypersensitivity reaction that can threaten the airway, breathing, and circulation

Recognize the pattern

oAirway

• Tongue or throat swelling

• Hoarse voice

• Stridor

Breathing

• Wheezing

• Respiratory distress

• Low oxygen saturation

Circulation

• Hypotension

• Tachycardia

• Dizziness or collapse

type II hypersensitivity

Antibody-mediated injury or altered cell function

Mechanism:

oIgG or IgM binds to antigens on a cell or tissue surface

oAntibodies activate complement, phagocytosis, or cellular destruction

oThe affected cell is damaged or its function changes

Common targets:

oRBCs, WBCs, platelets, tissue receptors

Clinical examples:

oAcute hemolytic transfusion reaction

oHemolytic disease of the newborn

oDrug-induced cytopenias

type III

Immune-complex-mediated tissue injury

Mechanism

oSoluble antigens combine with IgG or IgM antibodies

oAntigen–antibody complexes circulate through the bloodstream

oComplexes deposit in blood vessels or tissues

oComplement activation produces inflammation and tissue injury

Manifestations

oSystemic: Serum sickness, SLE, glomerulonephritis, vasculitis

oLocalized: Arthus reaction

type IV

Delayed, T-cell-mediated immune injury

Pathophysiology

oT cells recognize an antigen à

• Cytokines activate macrophages and other inflammatory cells à

  • CD8+ T cells may directly destroy target cells à

    • Tissue injury usually develops over 24–72 hours

Key point

oType IV hypersensitivity is delayed because T-cell activation and cellular inflammation take time to develop

Two clinical patterns

oDirect cytotoxicity

• CD8+ T cells destroy antigen-bearing cells

  • Example: immune-mediated hepatitis

oDelayed inflammation

• CD4+ T cells release cytokines

• Macrophages and other cells create local inflammation

• Examples: TST reaction and allergic contact dermatitis

Manifestations

oDelayed redness, swelling, induration, rash, or tissue injury after exposure

types of transplants

Autologous

oUses the patient’s own tissue (i.e. CABG) or blood

Syngeneic

oDonor and recipient are genetically same (i.e. identical twins)

Allogeneic

oDonor and recipient genetic and HLA profiles differ

oHLA matching can reduce, but not eliminate, rejection risk

Xenogeneic

oDonor and recipient are different species

Key point 

↑ genetic difference = ↑ potential for immune rejection

autoimmune diseases

Loss of self-tolerance causes immune-mediated tissue injury

Normal immune regulation

oSelf-reactive lymphocytes are eliminated, inactivated, or controlled

oThese safeguards help the immune system distinguish self from nonself

Autoimmunity

oSelf-tolerance breaks down

oB cells and T cells recognize self-antigens

oAutoantibodies and autoreactive T cells cause inflammation

Repeated injury damages organs and tissues

Examples

oSystemic lupus erythematosus

• Immune complexes and autoantibodies affect multiple organs

Rheumatoid arthritis

• Chronic immune-mediated inflammation damages synovial joints

Nursing connection

oAssess for inflammation, pain, fatigue, swelling, fever, organ dysfunction, and functional changes

Key point

oAutoimmune disease results from an immune response directed against the body’s own tissues

HIV is transmitted

Sexual Transmission

oExposure to infected body fluids during sexual contact

Blood Exposure

oSharing contaminated needles or exposure to infected blood

Perinatal Transmission

oTransmission from mother to infant during pregnancy, labor, delivery, or breastfeeding

Nursing Focus

oProvide education about prevention, testing, safer sex practices, and treatment during pregnancy

HIV infection

Primary infection phase (acute HIV infection)

oRapid viral replication, very high viral load

oPossible fever, fatigue, rash, lymphadenopathy, or other systemic symptoms

Seroconversion: the immune system responds and antibodies against HIV appear (1 to 6 months – also known as the window period)

Latency phase (chronic HIV infection)

oOngoing viral replication, progressive CD4-cell depletion without effective treatment

oMay be asymptomatic for an extended period

AIDS

oSevere immune suppression

oCD4 count below 200 cells/mm³ or an AIDS-defining illness

oIncreased risk for opportunistic infections and malignancies

Opportunistic Infections

oRespiratory infections

oGastrointestinal infections

oNeurologic infections

oOral candidiasis and other mucosal infections

Other Clinical Manifestations

oHIV-associated malignancies

oWeight loss and wasting

oNeurologic complications

oSkin and mucous-membrane lesions

Diagnosis

oFourth-generation HIV-1/2 antigen-antibody test

oHIV-1/HIV-2 antibody differentiation assay

oHIV-1 nucleic acid testing for confirmation

Prevention

Safer-sex education, barrier protection, HIV testing, avoidance of shared needles, and counseling

Pre-exposure prophylaxis (PrEP) when indicated

Prevention of perinatal spread

Treatment

Combination antiretroviral therapy, medication adherence, and follow-up care

Monitoring viral load and CD4-cell count

Prevention and treatment of opportunistic infections