PAMPs are molecules shared by many microorganisms but not present in mammals. A.
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PAMPs are molecules shared by many microorganisms but not present in mammals. A. True B. False Gamma globulin can be given as immunotherapy to confer artificial passive immunity. A. True B. False Activation of a B or T cell relies on 2 signals, which are: A. Antigen and antibody B. Haptens and carrier proteins C. Antigen binding and co-stimulation D. Antigen binding and tissue damage E. None of the above. Plasma cells A. secrete antibodies. B. function in Type IV hypersensitivity. C. directly destroy target cells. D. suppress immune reactions. E. activate B cells and other T cells. The ___ is considered a primary lymphoid organ. A. spleen B. lymph nodes C. thyroid D. pancreas E. thymus Lymphocytes constantly circulate between the blood, tissue and lymph environments; this circulation increases the chance they will find ___. A. Naive cells, which are important for the development of lymphoid organs B. Monocytes that will secrete survival enzymes C. Their specific antigen, or an antigen presenting cell displaying their specific antigen D. Other cells with the same specificity, which will form clusters under the mucosal tissue E. None of the above Select 3 cell types which Helper T cells can "help" stimulate. A. Natural Killer cells B. B lymphocytes C. Macrophages D. Basophils E. T lymphocytes After a bone marrow transplant, the recipient's blood type may change to the blood type of the donor. A. True B. FalseExplanation / Answer
1. True, PAMPs are molecules shared by many microorganisms but not present in mammals.
PAMPs (Pathogen-associated molecular patterns) are unique to microbes. These are microbial products which stimulate innate immunity by binding to receptors called pattern recognition receptors (PRRs). Mammalian cells do not have PAMPs, this is one of the reason why there is no autoimmune disease caused by innate immunity.
2. True, Gamma globulin can be given as immunotherapy to confer artifical passive immunity.
Artifically-acquired passive immunity is an immediate, but short-term immunization provided by the injection of antibodies, such as gamma globulin, that are not produced by the recipient's cells. These antibodies are developed in another individual or animals and then injected into another individual.
3. Antigen binding and co-stimulation are required for the activation of B or T cells.
MHCs (Major Histocompatibility Complex) present antigens to T-cell receptors (TCRs). TCRs cannot recognize an antigen unless it is presented by the MHC. When the TCR binds to the correct antigen-MHC complex the T-cell is activated. There are 2 main types of MHC, MHC I and MHC II. MHC I is present on all nucleated cells and activates CD8 T-cells. MHC II is present primarily on antigen presenting cells (APC) and activates CD4 T-cells. These APCs phagocytose extracellular pathogens, break them up into fragments, and then present those fragments on their surface MHC II for CD4 T-cells to recognize.
An antigen independent signal called the co-stimulatory signal is also required as well. Here CD28 surface molecules on the T-cell recognize B7 surface molecules on the APC. CD8 T-cells are activated by an interaction with a cell that has an intercellular infection. This infected cell can be of almost any type. The antigen is presented on the surface MHC I of the infected cell. To become active the CD8 cell must recognize the antigen and MHC. Both CD8 and CD4 cells require the same co-stimulatory signal ( B7 binding to CD28 ).
As for B-cells, there are 2 ways it can be activated, they are:
T-cell dependent B-cell activation in which inactive B-cell phagocytoses an extracellular pathogen and acts as the APC by presenting a fragment of the pathogen on its MHC II to the inactive T-cell, this leads to activation of the T-cell which then releases cytokines to active the B-cell.
T-Cell Independent B-cell Activation in which free floating antigen binds directly to the antiboies (B-cell Receptors) on the surface of the B-cell.
4. Plasma cells secrete antibodies.
Plasma cells are fully differentiated B-lymphocyte which produces a single type of antibody.
5. The Thymus is considered a primary lymphoid organ.
The thymus gland is the main organ of lymphatic system. The primary function of Thymus is to promote the development of T-cells. Whereas spleen and lymph nodes are secondary lymphoid organ.
6. Circulation of lymphocytes increases the chance of finding their specific antigen, or an APC displaying their specific antigen.
There are three types of lymphocytes, known as T cells, B cells, and Natural killer cells. T and B cells recognize antigens and is able to bind with them. Natural killer cells are also know as cytotoxic as they have the ability to kill other cells.
7. Helper T cells can help stimulate: B lymphocytes, macrophages, and T lymphocytes.
Helper T cells themselves, however, can only function when activated to become effector cells. they are activated on the surface of APCs, which mature during the innate immune responses triggered by an infection.
8. True, after a bone marrow transplant, the recipient's blood type may change to the blood type of the donor.
Bone marrow transplants are extensively matched in order to prevent rejection. However, because the Human leukocyte antigen (HLA) matching doesn't utilize blood type and the recipient's marrow is destroyed in the process, then is the donor's marrow produces different red blood cells, then the recipient's blood type may change to the blood type of the donor, with time.
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