Chapter 17

Body Defenses, Immunity, and

Vaccines

Functions of the Lymphatic System

Return cellular waste products and excess fluid from the tissues to the circulatory system.

Absorbs fats and fat-soluble vitamins from the digestive system and transport them to the cells.

Serves as an important part of the immune system.

Structures of Lymphatic System

• Lymph fluid and vessels• Lymph nodes• Tonsils and adenoids• Spleen• Bone marrow• Lymphocytes• Thymus• Immune system

Major structures and their primary functions

Lymph fluid and vessels – return cellular waste and tissue fluid to the circulatory system.• Lymph Vessels• Lymph capillaries• Right lymphatic duct and thoracic

duct• Lacteals

Thymus – produces T lymphocytes for the immune system.

Lymph nodes • Bean-shaped structures- site for

lymphocyte production. • produce lymphocytes and filter harmful

substances from lymph.• Major lymph node sites:• Cervical lymph nodes• Axillary lymph nodes• Inguinal lymph nodes

Tonsils and adenoids – protect the entry into the respiratory system.• Adenoids or nasopharyngeal tonsils.• Palatine tonsils• Lingual tonsils

Vermiform appendix and Peyer’s patch – protect against the entry of invaders through the digestive system.

Spleen – filters foreign materials from the blood.• Stores red blood cells, and maintains

the appropriate balance between cells and plasma in the body.• Forms lymphocytes and monocytes,

which are specialized WBCs with roles in the immune system.• Hemolytic - destroys old worn out

blood cells, acts as a blood reservoir, and stores platelets.

Functions of the Immune System

Defends the body against harmful substances such as pathogenic microorganism, allergens, toxins, and malignant cells.

It involves structures from many body systems.

Peyer’s patch

Common Diagnostic Tests

• ANA• Total complement,

C3 & C4• CRP• CD4 T-Cells *• ELISA• ESR • HLA-DW4

• LE Prep• PCR• RBC *• RF• Total White Blood

Cell count w/ differential *

• Western Blot

ANA

• Anti-Nuclear Antibody• Fasting for 8 hours prior• Antinuclear antibodies are produced and

act against the body’s own DNA• Causes tissue damage• Specific for SLE• Simple blood draw

Total Complement, C3 & C4

• Total complement refers to a group of 20 proteins in the blood

• Complement is important in the inflammatory process

• Main mediator in antigen-antibody reactions

• In SLE, large amounts of immune complexes are formed

• Just another simple blood test

CRP• C-Reactive Protein• Fasting for 8 hours• Red top tube (blood test)• CRP is an abnormal protein that

occurs in inflammatory disorders• Progressive increases correlate with

increases of inflammatory injury• CRP may be used to follow

therapeutic response medications

CD4 T-Cells

• A simple count of the number of CD4 cells present in a typical CBC

ELISA• Detects the antibodies that result

from exposure to HIV.• Antigens may be detected as early as

two weeks post exposure, and may remain for 2-4 months.

• Antibodies can take up to 1 year to detect.

• If ELISA positive, a repeat ELISA is done, with follow up by a Western Blot and Indirect Fluorescent Antibody (IFA)

ESR

• Erythrocyte sedimentation rate (ESR), a.k.a. Sed. Rate

• Measures the rate of fall of RBC suspended in plasma

• Results reported in millimeters per hour.

• Elevated levels are found in RA, AMI, gout, Lupus, Hodgkin’s disease & multiple myeloma

ESR

Vertical sed-rate pipettes

http://www.lt-burnik.si/LTB/wpe11.jpg

HLA-DW4

• Human Leukocyte Antigens (HLA) are classified into five series, designated A, B, C, D and D related.

• Each series contains 10-20 distinct antigens.

• Used to determine tissue transplant compatibility

LE

• Lupus erythematosus cell test• Assists in diagnosing lupus• ~75% of patients who have SLE will

have LE cells in their blood stream• LE cells are a result of immunological

activity against nucleoproteins.• It is only positive in about 50% of

clients and has a high false positive rate

Pcr• Plasma Creatinine• Approximately 98% of creatine is

contained in muscle, and about 1.7% is converted to creatinine.

• Skeletal muscle necrosis or atrophy causes a significant increase in serum creatine.

• Elevated levels are found with trauma, muscular dystrophy, poliomyelitis, amyotrophic lateral sclerosis, myasthenia gravis, starvation, hyperthyroidism, and diabetic acidosis.

RF

• Rheumatoid Factor• An IgM antibody directed against a

fragment of the IgG molecule• Useful as a test for autoimmune disorders

and particularly in the diagnosis of rheumatoid arthritis.

Western Blot

• Determines the presence of antibodies for human T-cell lymphotrophic virus type III AIDS virus (one of the several strains of the HIV virus)

• Fast, sensitive and exacting test for identifying the presence of antibodies to HIV

• But, a negative result does not prove the client has the disease, nor does a positive result prove the client will develop it!!