Clin Lab Med Exam 3 Review

3 lines of defense

3 lines of defense

1. nonspecific/innate = physical, chemical, & genetic barriers

2. nonspecific/innate = inflammatory response, interferons, phagocytosis

3. specific to a particular microbe = acquired immunity; B & T lymphocytes, antibodies, cytotoxicity

acquired immunity

immunity that the body develops after it overcomes a disease (natural), or through vaccination (artificial)

4 body compartments involved in immune function

1. reticulonendothelial system
2. blood stream
3. lymphatic system
4. extracellular fluid

reticuloendothelial system (RES) role in immunity

= fibrous network enmeshing each cells which connects one well to another tissue or organ
*provides a niche for phagocytic WBCs to crawl

circulatory system role in immunity

blood stream = blood cells + plasma

lymphatic system = vessels, lymph fluid, & lymph nodes

WBCs differentiate into specialized cells: granulocytes & agranulocytes

WBC granulocytes

-neutrophils: phagocytes
-eosinophils: destroy parasites, involved in allergic reactions
-basophils: release potent chemical mediators, involved with allergic reactions

WBC agranulocytes

-lymphocytes: B & T cells involved in specific immune response (key to 3rd line of defense)

-monocytes: phagocytes

B cell maturation

bone marrow

-when stimulated by antigens and cytokines from T-helper cells, they differentiate into plasma cells (which produce antibodies)

activated T cells can become what 4 cell types & what is their function?

= provide cell-mediated immunity

1. helper cells

2. supressor cells

3. killer cells

4. delayed allergy cells

*attack infected host cells, cancer cells, & foreign cells marked by antibodies

activated T helper cells

CD4
= signal B lymphocytes to produce antibodies and signal cytotoxic/killer T cells to kill tagged cells

stimulated cytotoxic T cells

CD8
= kill cells tagged for destruction

mature dendritic cells

= mature into highly effective processors and presenters of foreign proteins
*process antigens and present them to T helper cells

advantage of memory B cells

= remember the antigen and respond very rapidly on subsequent exposures

B cells become _____ when activated by an _____

plasma cells
antigen

= humoral immunity

plasma cells secrete _____

antibodies

IgG

= most prevalent antibody with numerous functions

-produced by memory B cells in response to second exposure

**only antibody capable of crossing the placenta

IgA

= secretory component of mucus and serous secretions
-confers specific local immunity to enteric, respiratory, & GU pathogens
-produced by plasma cells
-protects newborns passively from breast milk

IgM

= first class synthesized by plasma cells following the initial encounter with an antigen

-largest immunoglobulin

IgD

= serve as a receptor for antigens on B cells along with IgM
-may be the trigger for B cell activation

IgE

= interacts with receptors on mast cells and basophils

-involved with allergic reactions & parasitic infections

what is the only type of immunoglobulin that can cross the placenta?

IgG

opsonization

= a process in which microorganisms are coated with specific antibodies so that they will be more readily recognized by phagocytes to dispose of them

neutralization

= antibodies fill the surface receptors on a microorganism to prevent it from functioning normally

agglutination

= cross-linking antigens into larger clumps so that they are more easily found by antibodies

complement fixation

= interaction of an antibody with complement results in specific rupturing of cells & some viruses

4 types of immunodeficiency

1. B cell deficiency
2. T cell deficiency
3. combined immunodeficiency
4. acquired immunodeficiency

B cell deficiency

= inability of B cells to produce viable antibodies

T cell deficiency

= developmental failure of the thymus results in a few (if any) T cells and poor cell-mediated immunity

combined immunodeficiency

= lack of enzymes that produce T cell and B cell receptors leads to combined immunodeficiency
*rapidly fatal if severe

acquired immunodeficiency

= immune deficiency due to viruses (HIV), exposure to certain chemicals, radiation, or chronic diseases

what is the screening test you can quickly order in clinic to diagnose strep throat? What routinely needs to be sent out afterward to confirm the result?

1. rapid strep test - strep Group A
2. culture

what blood test can you order if a patient has a history of strep that you think may have gone untreated and turned into rheumatic fever, post-strep glomerulonephritis, or post-strep infection?

anti-streptolysin O titer (ASO titer)

what would you expect to see on a positive PPD test?

induration is > 2 cm in diameter
-larger erythema

what skin test can you order if you suspect your patient may have an immunodeficiency? what result would you see if your suspicion was right?

Candida albicans skin test

negative reaction = immunocompromised

how large of an increase from an acute to convalescent viral antibody titer would there be to suspect a viral infection?

4x or 4-fold increase

*you did have a prior infection

what screening test would you order to test for mononucleosis?

mono-spot
-detects heterophiles antibodies against the Epstein-Barr virus (EBV) in patient's serum
+ result = agglutination

interpret the following Mono-spot results
VCA-IgM: positive
VCA-IgG: positive
EA-D IgG: negative
EBNA, IgG: negative

= early, primary mono infection

interpret the following hep A virus (HAV) results
IgM anti-HAV: positive

= presence in blood indicates acute infection

interpret the following hep A virus (HAV) results
IgG anti-HAV: positive

= presence in blood indicates past infection (months-years) & immunity

what is the confirmatory test for a positive anti-HCV?

anti-HCV (RIBA)
-type of Western blot

what is the best screening test for syphilis?

rapid plasmin reagin (RPR) test
+ test = agglutination

what is the confirmatory test for syphilis?

FTA-ABS test (fluorescent treponemal antibody absorption test)

when would it be best to use an RPR test to screen for syphilis?

= useful to detect AND can help monitor treatment

-test becomes reactive within 1-4 week of infection

-becomes non-reactive/negative within 1 year of treatment

what test can you run from a CSF sample when you suspect late stage neuro-syphilis?

VDRL test (venereal disease research laboratory)
+ test = flocculation

what test can you order for suspected chlamydia?

EIA (enzyme immunoassay)
-urethral swab or urine sample that uses an antibody specific enzyme to detect the presence of an antigen
+ test = color change

what is the preferred method testing for HSV?

PCR test (polymerase chain reaction)
-fast & inexpensive that amplifies small segments of DNA

what is the downfall of ordering a Tzanck smear vs antibody testing for suspected HSV?

Tzanck - rapid diagnosis but CANNOT distinguish between HSV 1 and 2

antibody testing - CAN distinguish between HSV 1 and 2

what is the screening test for HIV?

EIA test

what is the confirmatory test for HIV?

Western blot test

antibodies in Type A blood

anti-B antibodies

antibodies in Type B blood

anti-A antibodies

antibodies in type O blood

anti-A and anti-B antibodies

antibodies in type AB blood

none

forward typing

= adding antibodies to the RBC sample to look for the antigen

type A: positive anti-A

type B: positive anti-B

type AB: positive anti-A & anti-B

type O: no antigens

interpret the following forward typing results:
anti-A: positive
anti-B: negative
anti-D: positive

Type A+ blood

reverse typing

= adding antigens/RBCs to the serum sample that contains antibodies

type A: positive for B cells

type B: positive for A cells

type AB: no cells

type O: positive for A & B cells

D-antigen

= Rh factor
Rh + means you have the D antigen (& anti-D antibodies)
Rh - means you lack the D antigen

what will happen to an Rh- mother when she is exposed to D-antigens from an Rh+ fetus during pregnancy?

her blood will develop anti-D antibodies

what is the most common cause of hemolytic disease of the newborn?

= Kell (K,k), Duffy (Fya, Fyb), & Kidd (Jka, Jkb) antigens

DAT or Coombs serum test is looking for the presence of what on the surface of RBCs?

= antibodies

DAT/Coombs test can help diagnose what conditions

1. hemolytic disease of the newborn (HDN)
2. investigation of hemolytic transfusion reactions
3. diagnosis of immune hemolytic anemias

type & screen

= used when the patient is not as likely to need a transfusion/blood products
-testing the patient's plasma for ABO, Rh factor, & unexpected antibodies

type & cross

= utilized when you know a transfusion is necessary
-patient/recipient serum is also crossmatched against donor RBCs

what type of blood can each blood type receive? universal donor & acceptor?

type A: can receive type A or O
type B: can receive type B or O
type AB: can receive type A, B, O, or AB = universal recipient
type O: can only receive type O = universal donor

when are washed RBCs given?

to patients who have serve reactions to plasma
-severe allergies, paroxysmal nocturnal hemoglobinuria, IgA immunization

when is fresh frozen plasma given?

= unconcentrated source of all clotting factors without platelets
to correct bleeding secondary to clotting factor deficiencies or in multifactor deficiency states
-massive transfusion, DIC, liver failure

when is cyroprecipitate given?

= concentrated FFP
used as a source of fibrinogen in acute DIC with bleeding & in other severe bleeding disorders

when is recombinant factor VII given?

for the treatment of hemophilia A

what is the first thing you should do when you suspect your patient is having a transfusion reaction?

STOP the transfusion

acute hemolytic transfusion reaction

= causes acute hemolytic anemia

signs & symptoms:

*pain at infusion site

-chest/back pain

-restlessness or anxiety

-nausea or diarrhea

febrile non-hemolytic transfusion reactions

*most common

= defined by a temp increase of 1 C or 1.8 F; antibodies in recipient's plasma react against antigens present on cell membranes of transfused granulocytes

signs & symptoms:

-temp increase, chills, headache, malaise, confusion

anaphylactic transfusion reaction

= reaction with recipient anti-IgA that occurs after infusion of only a few milliliters of blood/plasma

signs & symptoms:

-tachycardia, flushing, headache, chest pain, dyspnea

urticarial transfusion reaction

= occurs after febrile non hemolytic reactions; suspected allergy to donor plasma substances

signs & symptoms:

-local erythema, hives, itching, usually without fever

delayed hemolytic reaction

= high antibody levels 3-7 days after the transfusion (while initial screen was negative)

signs & symptoms:

-malaise, jaundice, fever, unexplained decrease in Hgb level, hemoglobinuria

CSF is analyzed in 4 tubes for what and in what order?

1. protein & glucose levels (chemistry)
2. Gram stain, meningitis PCR panel, cultures
3. cell count & differential
4. VDRL test (syphilis) or India ink stain

difference in findings between a traumatic LP & brain bleed

traumatic tap: red color is most intense in first tube
brain bleed/cerebral hemorrhage: even amount od red in ALL tubes

difference in findings between viral & bacterial meningitis

viral: high levels of lymphocytes
bacterial: high levels of neutrophils

what test can you utilize to assess the impairment of the blood-brain barrier and what results would indicate an impairment?

= CSF albumin index
impairment: index value > 9 (higher values are more severe)

what type of protein in the CSF would be indicative of MS? what other findings can support the diagnosis of MS?

= IgG (tested through CSF IgG index from a CSF total protein test)

-increased myelin basic protein (MBP)

-detection of oligoclonal bands (CNS IgG bands) using electrophoresis

-elevated lactate

what microbiology tests can be orders for CSF samples?

a) gram stain - bacterial & fungal meningitis

b) acid-fast stain - mycobacterial meningitis

c) india ink preparation - fungal meningitis caused by Cryptococcus neoformans

d) cultures - cases of meningitis

normal appearance of synovial fluid

clear, colorless to straw, does not clot

abnormal variants of synovial fluid

dark yellow: inflammation
green/yellow: bacterial infection
cloudy: elevated # of cells, organisms, or crystals
red: elevated # of RBCs

gout findings

= uric acid needle-like crystals

pseudogout findings

= calcium pyrophosphate rod-like or rhombic crystals

septic joint findings from a bacterial infection

= decreased glucose levels (they are using the glucose as food)

what information can you acertain from amniotic fluid examination?

-chromosomal defects
-neural tube defects (alpha-fetoprotein)
-hemolytic disease
-fetal pulmonary development (measures alveolar surfactant)

when/why is a Lecithin/Sphingomyelin (L/S) ratio test done?

= ratio estimates fetal lung maturity

-lethicin levels increase dramatically at gestational week 34 to develop/mature the lungs

-if there is a planned early delivery, L/S ratio > 2.0 is considered safe, otherwise the delivery is unsafe & meds may need to be given

transudative serous fluid

= body wide problem; an effusion that forms because of a systemic disorder that disrupts the balance in regulation of fluid filtration/reabsorption

ex. ascites

-SAAG > 1.1

-generally low WBC count

exudative serous fluid

= problem in the lining; an effusion that forms because of disorders that directly involve the membrane of the cavity that increases capillary permeability

ex. bacterial pneumonia, malignancies

-SAAG < 1.1

-generally high WBC count

normal semen results in an infertility work up

color: grayish-white & opalescent
volume: 2-5 mL
viscosity: initially viscous, but will become water within 60 mins
motility: > 50% motile sperm with moderate to rapid linear progression
count: 20-250 million sperm/mL
morphology: > 50% normal
pH: 7.2-7.8

when would you utilize a hemoccult test?

= when screening for increased amounts of blood in the stool (detects Hgb)

-utilizes guaiac impregnated filter paper

+ test: color change to blue/purple

*false + can appear after eating rare cooked meats/fish, vegetables (broccoli, turnips, cauliflower), fruits (cantaloup, bananas, pears, plums), or drugs that irritate the GI tract (aspirin, iron)

inflammatory vs non-inflammatory diarrhea

= microscopic examination of feces for presence of WBCs helps distinguish these
inflammatory: 1-3 cells per high power field

how do you test for candidiasis?

= tests for yeast infection by adding a drop of KOH to a smear of vaginal secretions
+ test: branching/budding organisms

how do you test for bacteria vaginosis (BV)?

= a drop of normal saline is added to a smear of vaginal secretions
+ test: "clue cells" or large squamous epithelial cells that are covered with bacteria

how do you test for trichomoniasis?

= a drop of normal saline is added to a smear of vaginal secretions
+ test: large, round or slightly oval organism with flagella that are usually motile

therapeutic range

blood level of a drug that correlates with the desired therapeutic effect in most patients

minimum effective concentration

below this level therapeutic effect is not achieved

minimum toxic concentration

above this level symptoms of toxicity appear

trough values of medications

= lowest concentration achieved during a dosing cycle

*most specimens drawn for therapeutic drug monitoring are trough specimens

peak values of medications

= highest concentration achieved during a dosing cycle
-should be below minimum toxic concentration