Flashcards in lab assessment Deck (68):
What are the three major proteins of natural immunity?
Interferon, Lysozome, Complement
What is the main fxn of the complement system?
Integral part of both the inflammatory process and host defenses against infection
What are the three ways complement can be activated?
classical, lectin, alternative
What is the key enzyme of complement activation where all three pathways converge?
What are the results of the activation of complement?
opsonization, inflammation, cytolysis
Describe classical pathway of complement activation
Activated when IgM or IgG antibodies bind to antigens (viral, bacterial or autoantigens)
C1: C1r and C1s.
Describe lectin pathway of complement activation
Similar to classical except that antibody is replaced by a lectin such as MBP. Activate C4 and C2
Describe the alternative pathway of complement activation
Does not require the presence of antibodies or lectins. Continuously activated at a low level
C3 binds to target
What does the C3b fragment do to the target?
Deposition of C3b marks the target for immune adherence and then elimination by phagocytic cells.
What does C3a, C4a, and C5a do to the target?
they're anaphylatoxins so they assemble the membrane attack complex
What happens as a result of the actions of complement?
Chemotaxis. Release of mediators.
Activation of macrophages, epithelial cells and most types of immunocompetent cells. Contraction of smooth muscles. Dilation of blood vessels. Exudation of plasma
When should you measure complement?
In cases of recurrent infection w/ normal WBCs and no immunosuppression. Diagnose Auto-antibody-mediated immune syndromes. Diagnose immune complex-mediated syndromes
What is an example of an auto-antibody mediated immune syndromes?
autoimmune hemolytic anemia
What some examples of immune complex-mediated syndromes?
lupus, Sjogren's glomerulonephritis
What is a CH50 test used for?
screening test to detect deficiencies in classical pathway. (lupus, RA)
What is the AH50 test used for?
screening test to detect deficiencies in alternative pathway
What are individual complement assays of C3 and C4 used for?
to determine whether deficiencies or abnormalities in the complement system are causing, or contributing to, a patient's disease or condition.
What are some diseases where you would see decreased complement levels?
Recurrent microbial infections, Autoimmune diseases, angioedema, Various types of kidney disease, Malnutrition, Septicemia, Serum sickness
What are commonly used tests for immunodeficiency?
CBC and differential. Antibody detection methods (IgM, IgG, IgA). Quantification and separation of Ig levels. Testing for cell mediated immunity
What does a CBC establish?
the presence or absence of lymphopenia, and any associated gross hematologic abnormalities
Describe a WBC and differential
Sensitive, but non-specific test that rises with bacterial, viral and some rheumatologic diseases
What are bands?
Less mature neutrophils that have recently been released from the bone marrow into the bloodstream. Nucleus is not segmented, but has a band or rod-like shape
When do you expect to see neutrophils and bands?
An increased need for neutrophils, as with an acute bacterial infection, will cause an increase in both the total number of mature neutrophils and the less mature bands.
What does the term shift to the left mean?
that the bands have increased, indicating an infection in progress
What is neutropenia?
a decrease in neutrophils
With what kind of infections would you expect to see a decreased neutrophil count?
viral diseases (hepatitis, flu, rubella, rubeola, mumps)
What are some types of medications that can reduce the neutrophil count?
antibiotics, lithium, phenothiazines, TCAs
When are decreases with eosinophil counts observed?
when a patient is receiving corticosteroid drugs.
What do basophils contain?
heparin, histamines, serotonin
What can cause an increase in basophil counts?
leukemia or Hodgkins
What can cause a decrease in basophil counts?
Corticosteroid drugs, allergic reactions, and acute infections
What substance do phagocytic monocytes produce?
What diseases cause monocytosis?
tuberculosis, malaria, Rocky Mountain spotted fever, monocytic leukemia, chronic ulcerative colitis and regional enteritis
What counts are done to test for AIDS?
T lymph counts
What is the expected difference btw neutrophil and lymphocyte counts in adults and children?
In adults, lymphocytes are the second most common WBC type after neutrophils. In young children under age 8, lymphocytes are more common than neutrophils.
What can cause an increase in lymphocytes?
many viral infections and with tuberculosis.
What can cause a decrease in lymphocytes?
Corticosteroids and other immunosuppressive drugs
What count of lymphocytes places a patient at very high risk for infection?
less than 500
What is the normal WBC count for adult?
What is the normal WBC differential for adults?
PMN—45-75% (about 70% normal)
lymphocytes—20-45% (about 30% normal)
The others all make up small percentages
What is neutropenia quantified as?
<1800 in adults
What are some etiologies of neutropenia?
overwhelming bacterial infections, viral, rickettsial and others like malaria. Drugs and chemicals (sulphas, antibiotics, analgesics). Ionizing radiation. Hematopoietic disorders. Hypersplenism
What is the ANC equal to?
the product of the white blood cell count (WBC) and the fraction of polymorphonuclear cells (PMNs) and band forms noted on the differential analysis.
What is lymphocytopenia quantified as?
ALC < 1500 in adults
What is the polyclonal response?
multiple plasma cells derived from different B cells produce heterogeneous antibodies (Ig)
What is the monoclonal response?
plasma cells derived from single antigen stimulated B cell, produce homogenous antibodies (Ig)
largest concentration of all immunoglobulins in the plasma. provides long-term immunity. Activates complement if conditions are optimal. Especially effective against encapsulated pathogens
is found in relatively small amounts. First antibody to appear in response to antigen
very good complement activator
first line of defense on mucosal surfaces. found in secretions. Protects against infections in urinary, GI, and respiratory tracts
Mediates allergic and hypersensitivity reactions
Activation of some lymphocytes not much known about it. Surface receptor of B lymphocytes
How do you test for antibody deficiency?
Routine measurement of IgG, IgA, and IgM. Measurement of serum IgD is not useful for the diagnosis of immune deficiency.
What does a direct immunoassay do?
Detect presence of antigens. May use enzyme immunofixation or immuno-fluorescence
Agglutination of antigen and antibody
What are some examples of direct immunoassay tests?
group A beta-hemolytic strep, H. influenza, S. pneumonia, N. meningitides
What is ELISA?
used to detect the presence of an antibody or an antigen in a sample.
What does an indirect immunoassay do?
Antigen provided—testing if pt antibodies are present
What are some examples of indirect immunoassays?
Monospot (heterphile): EBV antibodies. HIV antibodies. Hepatitis A, B, and C. Autoimmune diseases
How can agglutination be used to test for disease?
.Diseases can be diagnosed by a rising titer (antibody concentration in serum) or sero-conversion (from no antibodies to the presence of antibodies).
What does direct agglutination do?
test patient serum against large, cellular antigens to screen for the presence of antibodies. Direct agglutination reactions can be used to determine antibody titer.
What does indirect agglutination do?
To test patient serum for the presence of antibodies against soluble antigens serum is mixed with latex spheres with the soluble antigens attached.
What does SPEP do?
detect monoclonal immunoglobulinopathies by quantifying major grps of serum proteins
What serum proteins are quantified with SPEP?
Albumin. Alpha-1/2 globulins. Beta-globulins. Gamma-globulins
How do you interpret SPEP results?
Normally only albumin should be high, if others “spike” then abnormal and further tests need to be run
What does a CMI (cell mediated immunity) do?
Evaluates the integrity of cellular immunity.
What interactions does CMI depend on?
T cells. Macrophages. Other immunoreactants
What is cutaneous delayed-type hypersensitivity test (DTH) used for?
screening test in many instances of suspected cellular immune deficiency
What does a qualitative functional assay of CMI do?
Evaluate/measure localized skin reaction to intradermal injection of a battery of antigens. Anergy (lack of skin reactivity) indicates depressed CMI