Module 11 IMMUNITY BASICS, IMMUNODEFICIENCY & HIV/AIDS

Innate immunity

Natural, nonspecific defense present at birth

Acquired immunity

Immunity developed after exposure to antigen

Active natural immunity

Body makes antibodies after live pathogen exposure

Active artificial immunity

Body makes antibodies after vaccine

Passive natural immunity

Antibodies passed from mother to baby

Passive artificial immunity

Antibodies given via IgG injection

Hematopoietic stem cell

Multipotent cell that makes all blood cells

Myeloid stem cell

Becomes RBCs, platelets, granulocytes, monocytes

Lymphoid stem cell

Becomes T cells, B cells, NK cells

B lymphocyte

Matures into plasma cell, makes antibodies

T lymphocyte

Cell-mediated immunity

Plasma cell

Produces antibodies

Immunodeficiency

Underactive immune system, frequent infections

SCID

Severe combined immunodeficiency, congenital

CD4 count

Tracks immune function in HIV

HIV viral load

Monitors response to antiretroviral therapy

Bone marrow biopsy

Evaluates hematologic disorders

Flow cytometry

Profiles immune cells in immunodeficiency/malignancy

HIV

Retrovirus that targets CD4+ helper T cells

HIV transmission

Blood, semen, vaginal secretions, breastmilk, amniotic fluid

AIDS

Chronic condition from HIV with opportunistic infections/malignancy

AIDS incubation

Can be 10+ years, often asymptomatic until late

HIV high risk groups

Sexual contact, IV drug users, blood recipients, healthcare workers, infants of infected mothers

HIV window period

2-12 weeks, seroconversion occurring

HIV Stage 1

Primary infection, CD4 ≥500, flu-like symptoms

HIV Stage 2

Clinical latency, CD4 200-499, asymptomatic, can still transmit

HIV Stage 3

Symptomatic infection, CD4 <200, high viral load, opportunistic infections

Antigen/antibody test

Detects HIV as early as 2 weeks

HIV antibody rapid test

Detects infection by 2.5 weeks

Nucleic acid test (RNA)

Detects HIV as early as 10 days, expensive

Normal CD4 range

500-1500 cells/mm3

Plasma HIV RNA

Viral load, determines stage and treatment success

CMV

Viral opportunistic infection, causes retinitis leading to blindness

HSV

Herpes simplex virus, viral opportunistic infection

Tuberculosis (HIV)

Night sweats, weight loss, occurs with any CD4 drop

PJP

Pneumocystis jirovecii pneumonia, occurs at CD4 <200

MAC

Mycobacterium avium complex, common at CD4 <50

Candida albicans

White patches in mouth/throat, common in HIV

Toxoplasmosis

From contaminated meat/water/cat feces, causes neuro symptoms

Opportunistic infection prevention

Treated water, cooked food, safe sex, vaccines, avoid animal feces, take ART

Kaposi sarcoma

Cancer from HHV-8, linked to immunosuppression, elliptical skin lesions

Kaposi sarcoma risk

CD4 <200, corticosteroids, opportunistic infections

HAND

HIV-associated neurocognitive disorder, affects 20% of HIV patients

HIV encephalopathy early signs

Memory loss, headache, confusion, apathy, ataxia

HIV encephalopathy late signs

Global impairment, vacant stare, psychosis, seizures, death

PrEP

Pre-exposure prophylaxis, Truvada, for high-risk HIV prevention

PEP

Post-exposure prophylaxis, within 72 hours, Truvada plus Isentress/Dolutegravir

ART goal

Delay immune loss, decrease viral load, increase CD4, not curative

ART regimen

3 medications from at least 2 drug classes