CHT EXAM COMPLETE STUDY GUIDE questions and
answers A+ Grade 2026\2027
It is possible to convert the plasma
into serum by recalcifying the plasma and allowing coagulation to occur.
- correct answer Calcium is added to the plasma to form a complex with the citrate present in the anti-
coagulant. This restores a normal
ionized calcium level allowing clotting to occur.
Polyspecific antiserum
can be______ with lymphocytes to determine if there is a single antibody or multiple
antibodies.
- correct answer absorbed
Another application of lymphocyte
absorption is to use the patient's own cells to remove_____. Absorption can be performed
at cold or warm temperatures depending on the type of antibody.
- correct answer autoantibody
_________ are typically
cold reacting (4oC) and________are typically warm reacting (22-37oC).
- correct answer Autoantibodies
B cell antibodies
Patient serum may contain autoantibodies and/or IgM antibodies that may interfere the binding of
anti-HLA IgG antibodies to the antigen. In complement dependent assays (CDC), IgM antibodies
,can activate complement; potentially leading to ___________.
- correct answer false positive reactivity.
DTT
- correct answer dithiothreitol, also known as Cleland's Reagent
DTT inactivates IgM molecules by cleaving the _________ in the
pentamer structure.
- correct answer disulphide bonds
Heat inactivation works by cleaving the disulphide bonds in the
pentamer structure, but is less specific than _____.
- correct answer DTT.
ALA
- correct answer therapeutic antilymphocyte
antibodies
Thymoglobulin
- correct answer purified, pasteurized, gamma immune globulin,
obtained by immunization of rabbits with human thymocytes
OKT3
- correct answer a murine IgG monoclonal antibody directed against CD3
If these therapeutic antilymphocyte
antibodies are present in the patient serum, they can cause_______ reactivity in
T cell cytotoxic assays.
- correct answer false positive
,ALA removal is accomplished by absorption using _____coated with anti-rabbit or anti-mouse
immunoglobulin for Thymoblobulin or OKT3, respectively.
- correct answer magnetic beads
serum preparations
- correct answer 1. Recalcificiation of plasma
2. Adsorption with lymphocytes
3. Inactivation of IgM antibodies
a. DTT treatment
b. Heat Inactivation
4. Depletion of therapeutic anti-lymphocyte antibodies from serum
Why is calcium added to plasma to convert it to serum?
- correct answer Calcium is added to the plasma to combine with the citrate present in the
anticoagulant.
This restores a normal ionized calcium level and allows clotting to occur.
At what temperature should serum absorption with lymphocytes be performed?
- correct answer Typically, auto-antibodies are cold reacting and should be absorbed at 4oC while
alloantibodies
are warm reacting and should be absorbed at 37oC.
DTT treatment is more specific than heat treatment in
removing IgM antibodies. However, DTT can also affect the _______ in IgG antibodies.
- correct answer disulfide bonds
What happens if we don't remove OKT3 prior to cytotoxicity assays?
- correct answer OKT3 is a monoclonal antibody directed against the CD3 molecule. Therefore, the
binding of OKT3 to any CD3+ cell will activate complement and lyse the target cell. This results
in falsely positive reactivity.
, Lymphocytes have a density of_______
- correct answer ~1.077 g/ml.
Cells with a higher density than FH
- correct answer red cells and granulocytes
cells of a lower density than lymphocytes
- correct answer platelets
isolation of cells from lymph nodes or spleen is normally fast and simple and leads to greater _____ and
______
- correct answer cell yield
viability.
Obtaining lymphocytes from spleen will require
an additional FH step along with purification steps due to a large number of contaminating cells,
such as _______ ,______ and _______.
- correct answer macrophages
erythrocytes
platelets.
intrinsic cell properties
- correct answer cell size and
granularity of the cell.
One method of lymphocyte isolation (HP) utilizes an intrinsic cell property, __________, by using a
density gradient medium.
- correct answer cell density
extrinsic cell properties
- correct answer cell surface marker, phagocytic capabilities and
adherence capabilities.
answers A+ Grade 2026\2027
It is possible to convert the plasma
into serum by recalcifying the plasma and allowing coagulation to occur.
- correct answer Calcium is added to the plasma to form a complex with the citrate present in the anti-
coagulant. This restores a normal
ionized calcium level allowing clotting to occur.
Polyspecific antiserum
can be______ with lymphocytes to determine if there is a single antibody or multiple
antibodies.
- correct answer absorbed
Another application of lymphocyte
absorption is to use the patient's own cells to remove_____. Absorption can be performed
at cold or warm temperatures depending on the type of antibody.
- correct answer autoantibody
_________ are typically
cold reacting (4oC) and________are typically warm reacting (22-37oC).
- correct answer Autoantibodies
B cell antibodies
Patient serum may contain autoantibodies and/or IgM antibodies that may interfere the binding of
anti-HLA IgG antibodies to the antigen. In complement dependent assays (CDC), IgM antibodies
,can activate complement; potentially leading to ___________.
- correct answer false positive reactivity.
DTT
- correct answer dithiothreitol, also known as Cleland's Reagent
DTT inactivates IgM molecules by cleaving the _________ in the
pentamer structure.
- correct answer disulphide bonds
Heat inactivation works by cleaving the disulphide bonds in the
pentamer structure, but is less specific than _____.
- correct answer DTT.
ALA
- correct answer therapeutic antilymphocyte
antibodies
Thymoglobulin
- correct answer purified, pasteurized, gamma immune globulin,
obtained by immunization of rabbits with human thymocytes
OKT3
- correct answer a murine IgG monoclonal antibody directed against CD3
If these therapeutic antilymphocyte
antibodies are present in the patient serum, they can cause_______ reactivity in
T cell cytotoxic assays.
- correct answer false positive
,ALA removal is accomplished by absorption using _____coated with anti-rabbit or anti-mouse
immunoglobulin for Thymoblobulin or OKT3, respectively.
- correct answer magnetic beads
serum preparations
- correct answer 1. Recalcificiation of plasma
2. Adsorption with lymphocytes
3. Inactivation of IgM antibodies
a. DTT treatment
b. Heat Inactivation
4. Depletion of therapeutic anti-lymphocyte antibodies from serum
Why is calcium added to plasma to convert it to serum?
- correct answer Calcium is added to the plasma to combine with the citrate present in the
anticoagulant.
This restores a normal ionized calcium level and allows clotting to occur.
At what temperature should serum absorption with lymphocytes be performed?
- correct answer Typically, auto-antibodies are cold reacting and should be absorbed at 4oC while
alloantibodies
are warm reacting and should be absorbed at 37oC.
DTT treatment is more specific than heat treatment in
removing IgM antibodies. However, DTT can also affect the _______ in IgG antibodies.
- correct answer disulfide bonds
What happens if we don't remove OKT3 prior to cytotoxicity assays?
- correct answer OKT3 is a monoclonal antibody directed against the CD3 molecule. Therefore, the
binding of OKT3 to any CD3+ cell will activate complement and lyse the target cell. This results
in falsely positive reactivity.
, Lymphocytes have a density of_______
- correct answer ~1.077 g/ml.
Cells with a higher density than FH
- correct answer red cells and granulocytes
cells of a lower density than lymphocytes
- correct answer platelets
isolation of cells from lymph nodes or spleen is normally fast and simple and leads to greater _____ and
______
- correct answer cell yield
viability.
Obtaining lymphocytes from spleen will require
an additional FH step along with purification steps due to a large number of contaminating cells,
such as _______ ,______ and _______.
- correct answer macrophages
erythrocytes
platelets.
intrinsic cell properties
- correct answer cell size and
granularity of the cell.
One method of lymphocyte isolation (HP) utilizes an intrinsic cell property, __________, by using a
density gradient medium.
- correct answer cell density
extrinsic cell properties
- correct answer cell surface marker, phagocytic capabilities and
adherence capabilities.
