T cells have to work in a partnership with an Antigen Presenting Cell (APC). Before this can occur, the APC must modify the antigen. Please discuss how this process happens and the major protein that is involved. Be detailed.

Identify which of the following statements regarding naive T cells is incorrect. a. Naive T cells have the capacity to survive for many years as nondividing circulating cells in the absence of specific antigen. b. Naive T cells express LFA-1 molecules that change their conformation after encountering a specific peptide:MHC complex. c. Naive T cells exit from lymph nodes using the same route as effector T cells. d. Naive T cells express ICAM-3, which binds to DC-SIGN on dendritic cells with high affinity. e. Naive T cells express high levels of S1P receptors on their surface.

All of the following statements concerning regulatory T cells (Treg) are correct, EXCEPT: The regulatory cytokines produced by regulatory T cells are IL-12 and TGF-B O Thymocytes that recognize self-antigen in the thymus with a certain affinity become natural (central) regulatory T cells O In the periphery T cells that recognize self-antigen in the presence of TGF-B become induced regulatory T cells O A Treg cell can suppress self-reactive lymphocytes that recognize peptides different from that recognized itself provided that the peptides are derived from the same tissue O A Treg cell can suppress self-reactive lymphocytes that recognize peptides different from that recognized by itself provided that the peptides are presented by the same antigen-presenting cell (APC)

True / False: Affinity maturation is the process by which the affinity of BCRs and TCRs produced in response to antigen increases with prolonged orrepeated exposure to that antigen. True / False: TLRs are only expressed on the cell surface, and function to detect PAMPS and DAMPS. True / False: T cells undergo positive, but not negative, selection during cellular development. True / False: The Fc portion of antibodies consist exclusively of the heavy chain. True / False: ADCC relies on the activity of mostly basophils or mast cells.

Describe the differences in how an antigen presenting cells (APC) activate a Helper T versus a Cytotoxic T cell.

What three specific cells chickenpox may encounter which are a part of the second line of defense? For these three cells discuss their function, how they can detect chickenpox, and what they do to remove the chickenpox.   (Discuss any receptors the immune cells have, chemical mediators, enzymes, etc. which are used to detect and remove the antigen.)

Individuals or mice with defects in the biochemical pathways needed for loading peptides onto MHC molecules show greatly increased susceptibility to virus infections. Experiments examining the MHC molecules present on the surface of host cells in these individuals would show: Normal numbers of MHC molecules expressed on host cells, but no peptides bound to them. Very low levels of total MHC proteins expressed on the cell surface. Normal numbers of MHC proteins on the surface but all of them bound to self-peptides not pathogen peptides. Very high levels of total MHC proteins expressed on the cell surface. Only virus-infected cells expressing high levels of MHC proteins on the cell surface.

Addition of immunoglobulin G (IgG) specific for hemoglobin to a solution of hemoglobin results in the formation of a red precipitate. In contrast, addition of the Fab fragments from this antibody to hemoglobin results in no such precipitate. What could explain this difference in results? Treatment with papain produces Fab fragments with different antigen specificity than the original IgG molecule. IgG can simultaneously bind two different antigens, whereas an Fab fragment can only bind one antigen at a time. The Fab fragments preferentially bind to other Fab fragments rather than to hemoglobin. The hemoglobin molecule antibody-binding sites can bind IgG molecules, but cannot bind Fab fragments.

Name one of the thymic hormones that help direct the maturation and specialization of T cells.

True/False: Neutrophils regulate the production of active cathelicidins (a class of antimicrobial peptides) by segregating the inactive propeptide from the processing enzyme that cleaves and activates it in two different types of cytoplasmic granules. These two types of granules are induced to fuse with phagosomes after ingestion of microbes, bringing the processing enzyme and the propeptide together.