module 03 section 01 (Igs) Flashcards
lymphocytes develop from a common stem cell through which process?
lymphopoiesis - the differentiation of lymphoid cells from a hematopoietic stem cell
what factors (generally) detmermine the multi-step process of lymphopoiesis?
singals conveyed by cell-cell interactions and soluble factors
what are the effector molecules of humoral immunity
immunoglobulins (antibodies)
immunoglobulins are glycoproteins, true or false?
if false what type of protein are they?
true
what are the two ways antibodies function (hint: where are the two places they can be found)?
they can be secreted by plasma cells (differentiated B-cells) OR serve as the antigen-binding receptors on b-cell membranes
what are the two types of antibodies?
monoclonal and polyclonal
describe monoclonal antibodies
antibodies that are derived from a single B-cell clone and are therefore specific for a single epitope on an antigen
describe polyclonal antibodies
a heterogenous mixture of antibodies with different anfinity produced by many clones of B-cells, recognizing multiple epitopes on antigens
what is the hallmark of our immune system?
the precision - one antibody specific for one particular microbe
what is the primary function of immunoglobulins?
to bind specifically to antigens (necessary for protection of the host)
how do antibodies act when expressed on the surface of B-cells?
act as receptors mediating antigen-triggered activation of the cell
how do antibodies act when secreted into the blood by plasma cells?
act as mediators of specific humoral immunity by binding to antigens
what are effector functions?
secondary function of immunoglobulins:
on top of their primary function, soluble immunoglobulins also elict a variety of biological responses through interactions with varius other cells (including phagocytic cells, mast cells, basophils)
list 2 effector functions of soluble immunoglobulins
(1) binding to t-cells as part of antibody dependent cell cytotoxicity
(2) binding to C1 complex in complement fixation, resulting in lysis of cells, release of biologically active molecules, and clearance of immune complexes in the blood
can the presence of a certain type of antibody be used as a diagnostic tool? why or why not?
yes - antibodies are produced in response to an infection, illness or irregularities in self cells
what is an ELISA test?
enzyme linked immunosorbent assay; a labratory test that detects the presence of a particular antibody in the blood of an individual through analysis of the antiserum
what is antiserum?
serum containing antibodies that bind to a particular antigen
when preforming an ELISA it is necessary to centrifuge the blood samples, why?
to precipitate the blood cells and obtain the clear fluid known as serum - any cells that remain will interfere with the assay and may influence results
what was the prodecure for the ELISA lab example in the module? (9 steps)
- blood samples were centrifuged
- blood samples were diluted (1:2, 1:10, 1:100) using buffer
-blood samples were added to the plate - positive control (anti-dna primary antibody) and negative control (buffer) are added to the plate
** everything was added in triplicate ** - incubate the ELISA plate at 37 degrees for 15 mins, then remove
(insures reaction occurs properly - 37 = body temp) - remove fluid from each well of the ELISA and wash with PBS
- add buffered solution containing secondary antibody that recognizes the antibodies made in humans
(secondary antibody is made in rabbits and has HRP enzymes) - incubate the plate again at 37 degrees for 15 mins
- remove fluid from each well and wash with PBS
- add buffered solution containing the chemical (HRP) substrate
- if there are human antibodies present the clear substrate will turn yellow
- time for 15 mins
- if all three triplicates are yellow - probably has it
- if only two - probably has it but requires more testing
- if none - probably does not have it
what is the ELISA result of a patient who’s results show that the antibody is present, however, the patient is not sick (as they may have already had the disease but recovered)?
true positive
what is the ELISA result of a patient that may be a poor producer of the antibody, or have some interfering substance in their blood, or the amount of anitbody is too low to measure accurately or goes undetected?
false negative
what is the possible ELISA result for a patient who has an unrelated antibody that reacts with the desired antigen non-specifically?
false positive
why are diltuions of sera used in ELISA testing?
results are based on color saturation of the enzyme attached to the second antibody, so using multiple dilutions helps gauge the level of antibody in the sample
why are ELISA tests done at 37°C?
what would happen if the test was done above 37°C?
what would happen if the test was done below 37°C?
because in order to obtain the correct results, the testing environment must mimic the environment of the human body, and body temp is 37°C
- too high: denaturation
- too low: reaction wont proceed
- either way would get a false neg
