Autoimmunity 1 Flashcards
Are natural killer cells part of the innate or the adaptive immunity?
innate
Contrast cell mediated and humoral adaptive immunities.
cell mediated defends against intracellualr microbes (Tcell mediated) while humoral defends against extracellular microbes and toxins (B-cell/antibody mediated)
What is the action of the T-cell receptor (generally speaking)
TCR recognizes peptide antigen with MHC on cells (each T cell clone is specfic to certain antigen
How can you tell if a group of T-cells is malignant?
if they are all clones, ie. No rearrangement of TCR, the group of cells is malignant
What cluster differentiation molcule is used as a T-cell marker?
CD3 is linked with TCR and s specific T-cell marker
What are the two subsets of cell types a/B associated with TCR?
CD4 (helper Tcells) and CD8 (cytotoxic T-cells
What types of cells to CD4 and CD8 cells bind to?
CD4 bind to class II MHC on APC’s, CD8 bind class I on any cell
If a Tcell doesn’t express a/B with its TCR, what other set of proteins does it likely express?
a minority of T cells have gamma/delta TCR and do not require MHC for antigen recognition
What CD molecule do both CD4 and CD8 cells express?
CD3, they are both T-cell subtypes
What is needed for T-cell activation.
T-cells need two signals for activation both antigen/MHC combination engaging TCR/CD4 or 8 AND CD28 engaging B7 on APC
Without second signal, T-cells …
fail to respond, undergo apoptosis or become unreactive (anergic)
Once activated T-Cell produce what cytokine?
IL-2 which acts to activate other T-cell and as a self-stimulant, this stimulation causes B cell differentiation into effector and memory cells
What molecule is used in clinical cell typing?
MHC molecules
MHC class II molecules are present on only what type of cell?
antigen presenting cells, in contrast with MHC class I cells which are present on all nucleated cells
Approximately 60% of mature Tcells are CD4+ ____ T-cells tha secrete ____ to help macrophages and B-cells fight infection.
helper T cells; cytokines
About 30% of T-cells are CD8+ ____ T-cells that destroy host cells that ______ _____.
cytotoxic T cells; contain pathogen/ present pathogen
Contrast the action of CD4+ helper T cells and CD8+ cytotoxic T cells
CD4+ secrete cytokines and act as mast regulators of virtually all immune cells while CD*+ cells kill other cells
What are the 3 functionally distinct CD4+ T cell populations?
TH1 cells, TH2 cells and TH17 cells
Contrast the secretions of TH 1,2, and 17 cells
TH1 secrete interferon gama , TH4 secrete IL-4 and IL-5 and T17 cells secrete IL-17
What is the action of TH1 cells
macrophage activation and stimulation of opsonizing IgG antibody production
What is the action of TH2 cells?
stimulate IgE and eosinophil activation
What is the action of TH17 cells?
recruit neutrophils-acute inflammation and monocytes
B-cells arranged in aggregates are called ____ ____
lymphoid follicles
Describe the specific receptors used by B-cells to recognize antigen.
surface antibodies IgM and IgD bind the antigen
Once stimulated, B cells become ___ ____ which secrete ____
plasma cells, immunglobulins (antibodies)
How are macrophages/monocytes activated?
activated by INF-gamma produced by TH1 CD4+ T cells
What MHC class are macrophages? What process increases phagocytosis by macrophages?
APC with Class II MHC, phagocytosis is increased by opsonization of microbes by factors like IgG and C3b
Name the two different types of dendritic cells.
interdigitated and follicular dendritic cells (some overlapp)
Describe the characteristics of interdigitating dendritic cells.
IDC are the most important APC for primary repsonse, located in the epithelium/interstitium and have numerous fine process which increase SA and MHCII and antigen receptors
Describe the characteristics of a follicular dendritic cell.
important APC for ongoing immne response, located in the germinal centers of lymphoid follicles and trap bound antigen with Fc, IgG and C3b receptors and present antigens to B cells for activation
What is the action of natural killer cells?
aka large granular lymphocytes, they kill virally infected and tumor cells; but do not require prior sensitization
What are the two ways that NK cells recognize and target other cells?
- antibody dependent cell mediated cytotoxicity (with CD16 as an Fc receptor for IgG) and 2. monitoring of class I MHC molecules
Describe the inhibitory signal of NK cells.
if cell presents a self/class MHC complex, this binds the NK inhibitory receptor, viruses inhibit MHC expression, which means inhibitory receptor is not engaged and cell is killed
