This blog is added to the MIR Project 2.0 to correct the quiz this year's MIR collaboratively among professionals in the field Twit-Blog & Health. Below are three questions of Immunology and reasoned explanation of the answers that I correct. In the coming days also publish the answers to the questions of genetics, for which count on the collaboration of Dr. Ejarque, FCM specialist, Clinical Biochemistry and Clinical Genetics MIR Italian.
Immunology Questions:
VERSION 1: QUESTION 207: selective depletion of T cells with monoclonal antibodies anti-CD3 complement fixing is useful in:
1. Ell preventing graft rejection in allogeneic or histoincompatible.
2. Induction of specific immunity to viral infections.
3. Generation of cytotoxic cells and natural killer (NK, Natural Killer).
4. Induction of specific foul against intracellular bacteria.
5. Prevention of acquired and innate immune defenses.
Monoclonal antibodies are immunoglobulin molecules of identical specificity produced in the laboratory following the merger of selected B cell with a normally functioning cell myeloma. This question is only necessary to know that the Cluster of Differentiation 3 (CD3) is a marker of T lymphocytes, and that if we introduce specific antibodies (eg OKT3), we will be marking the T lymphocytes as a target to eliminate the own immune system, so they get a depletion and hence a result of immunosuppression. The correct answer would be number 1 because if we can inhibit the T lymphocytes would not take place against acute rejection antigens do not own that carry the transplanted tissue, which is a rejection mechanism mainly orchestrated by T lymphocytes The other options would be false once defined the mechanism of action of anti-CD3 monoclonal antibody.
VERSION 1: Q 209: What molecules or immune system cells used in its initial phase the immune response of a healthy individual against a microorganism which has not previously infected
1 . IgG antibodies with high affinity for peptidoglycan antigens.
2. TH2 lymphocytes in the lymph nodes.
3. Cytotoxic T lymphocytes (CD3 + CD8 +).
4. -Like receptors "toll" (TLR) phagocytes.
5. The circulating memory T cells.
To correctly answer this question we need to know the function at the time of the cells and molecules in the defense against invading antigens not previously identified. It should be clear to do that faster and initial responses to intrusions of this kind are those that are less effective and less specific, which are by definition the answers provided by innate immunity mechanisms. Taking this concept present rule out the option 1 (adaptive immunity), option 2 (adaptive immunity), option 3 (immunity adaptive) and Option 5 (no circulating memory T cells). The correct answer would be option 4, it is the only one of the boards that mentioned a mechanism of innate immunity. TLRs are pattern recognition receptors expressed by leucocytes and microorganisms in general and not your own cells. TLRs induce an intracellular signaling cascade that induces the secretion of cytokines such as TNF, IL.1, IL-12, etc and the expression of costimulatory molecules such as CD80 to participate in the development of a more specific defense strategy against invading organism .
VERSION 1: 222 Q: Which of the following driving positive selection of thymocytes?
1. Self-tolerance to self proteins.
2. Clonal deletion.
3. Autoimmunity against self proteins.
4. Restriction by histocompatibility molecules themselves.
5. Immunization against intracellular pathogens.
Positive selection is a control procedure in the process of T cell maturation that ensures the survival of those thymocytes that recognize self-MHC molecules. Thymocytes are cells immature CD4 + CD8 + that have been produced without any contact with antigens. In their maturation have only been able to express a TCR that interacts weakly with MHC molecules of thymic epithelial cells are selected to circumvent the programmed cell death and continue the maturing process. This mecansimo is known as positive selection and gives rise to thymocytes expressing a TCR able to recognize and interact weakly with self-MHC molecules. The correct answer is option 4. Option 1, incorrect in this question refers to the result of another process in the maturation of thymocytes, negative selection, which involves induction cell death that despite those thymocytes expressing a TCR that recognizes and interacts with self-MHC molecules, it does so through high affinity interactions, thus preventing the production of highly reactive T cells against their own structures (self-tolerance.)
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