Immunology Flashcards
What evidence is there that tumors are immunogenic?
1 higher incidence immunodeficient patients-congenital, AIDS, drug induced
2 Tumors infiltrated with lymphocytes have a better -prognosis-TIL have reactivity against tumor Ag
3 Spontaneous regression-reported in all tumor types
4 Development of tumor vaccines-HPV and HBV. Require: ID tumor Ag, induce a T-cell mediated response (not Ab)
5 Animal models of tumor rejection-
6 Paraneoplastic syndromes-Tumor induces an immune response that cross reacts with other tissue
A tumor specific immune response implies the presence of tumor associated antigens. These are of 4 types, explain each.
Altered self-mutated protein inducing an immune response
Re-emergence of fetal Ag-carcino embrionic Ag (CEA), and alpha feto protein (AFP).
Oncogene products-p53 etc
Virally associated Ag- HPV and HBV
What are the players of the innate and adaptive immune response that are anti-tumor?
Innate- DC; inflammation and NK cells
Adaptaive- CD8+ major response. Complement ADCC minor
How do NK indirectly lyse tumor cells? Directly ?
via ADCC using anti tumor Ab made by B-cells. NK can bind Fc portion of the Ab and release cytokines like IFN-Gamma, or granzymes to killed the tumor cell. This is like opsonization, except tumor cells are not being targeted for phagocytosis but rather destruction. This is the process by which paralytic worms are killed by eosinophils when covered in IgE.
Directly by fixing complement on malignant cells
Your patient has hepatocellular carcinoma. What ratio of immune cells would likely give them a more favorable prognosis?
A low IFN gamma, high T-reg
B high T-reg, low CD8+
C high CD8+, low T-reg
D low CD8+, low IFN- gamma
C High CD8+, (and low T-regs)
Why are tumors not rejected by the immune systems response?
Some tumors are weakly immunogenic
Lack MHC (which decrease CD8+ immune response), or co-stimulators signal from B7 which will lead to CD8+ T-cell anergy.
Secretion of Immunosuppressive factors- IL-10, TGF-B, VEGF, PGE2
Immunodeviation- cytokines stimulating CD4 differentiation to Tfh and B-cell response rather than Th1 and CD8+ response.
T regs inhibits CD4 and CD8 cells
Describe immunotherapies in terms of passive, active, as well as specific types
passive-short term: cytokines, Lymphocyte activated killers (general T-cell activation; LAK), tumor infiltrating lymphocytes (TIL). Mab (toxin, radiolabeled, prodrug conversion, chimeric)
Active/long term: cancer vaccines- inhibition of CTLA-4 so that CD28 can provide second signal to APC by binding to CD80,86 and activating T-cell response. CTLA-4 binding would not activate T-cell response.
CD80/86 aka______, can bind to which two receptors, that have what functions?
B7
Bind to either CD28 stimulates T-cell or CTLA-4 which acts as an off switch to T-cell function.
RBC incompatibility of the ABO blood type stimulates the immune system to produce what type of antigens? What type of immunoglobulin response will occur; can it cross the placenta?
Carbohydrates, this will produce a IgM response and these immunoglobulins can’t cross the placenta.
Antigens to glycoproteins (Rh) however will stimulate T-cells to become Tfh cell and class switch Ab to IgG which can cross the placenta.
Type A, B, AB and O blood produce what antigens?
A-B
B-A
AB-none
O-both
Why is it bad that an Rh negative mother be exposed to her Rh positive babies blood?
The Rh + blood will generate a T-cell response to the Rh+ Ag that will result in IgG production. This immunoglobulin will cross the placenta and attack the fetal blood cells. This usually occurs with the second Rh+ child after the mother has been exposed to Rh+ Ag during the first birth.
What is the Coombs direct and indirect test?
The direct test, tests the fetal blood for attachment of anti Rh Ab and uses a Rabbit anti-human Ig to agglutinate these attached cells.
The indirect test, tests the mothers serum for anti Rh+ Ab by exposing her blood to Rh positive blood. Also an agglutination test.
How do you prevent an Rh negative mothers body from rejecting her Rh+ fetus?
Inject mother with Ab (IgG) to Rh+ antigen (RhoGAM) shot This will prevent her from becoming sensitized to her next child .
Which of the following is not associated with accelerated disease progression in hep C?
Alcohol hep B co infection HIV co infection Disease acquisition later in life Hep C RNA level
Hep C RNA level surprisingly
