Basic Immunopathology Flashcards
2 Categories of normal immune response
1- Innate response
2- Adaptive response
Innate response
1- inflammation
2-anti-viral defenses
Always present
First line of defense
Epi cells, pahocytic cells, dendritic cells, and a cells ,Innate lymphoid cells, several plasma proteins
Pattern recognition receptors
What are the types of receptors and cells that involved in Innate response
Toll like receptors
NOD-like receptors
C-type lectin receptors
RIG-like receptors
Pattern recognition receptors
Epithelia
Monocytes and neutrophils
Dendritic cells
Innate lymphoid cells
Natural killer cells
Plasma proteins
What is the role of Toll-like receptors in innate response
Leukocytes,ep, cells recognize components of microbes by these receptors
Presenter in plasma membrane and endosomal vesicles
What are the roles of NOD-like receptors in innate response
Intracellular sensors of PAMPs
What are the roles of C-type lectin receptors in innate response
On the plasma membrane of macrophages and DCs detect fungal glycans and elicit inflammatory reactions to fungi.
What are the roles of RIG-like receptors in innate response
Located in the cyt Oslo,detect nuclei acids of viruses that replicate in the cytoplasm of infected cells.
What are the roles of pattern recognition receptors in innate response
Plasma membrane receptors detect extra cellular microbes
Endosomal receptors detect ingested microbes
Cytosolic receptors detect microbes in the cytoplasm
What are the roles of epithelia cells in the innate response
Mechanical barrier
produce anti microbial mol. (Defensins)
Lymphocytes located in the epi.stop microbes
What are the roles of monocytes and neutrophils in the innate response
Monocytes that enter to tissues and mature — macrophages — antigen presenting
Senses the presence of microbes
Ingest and destroy them.
What are the roles of dendritic cells in innate response
Presentation of ag — capture protein ag, display peptides for recognition by T lymphocytes
Secretion of cytokines— in inflammation and antiviral defense
What are the roles of Innate lymphoid cells in innate response
Natural killer cells— early protection
Tissue resident lymphocytes don’t have T-cell ag receptor
Sources of inflammatory cytokines during early phases of immune reactions
Cannot respond to ag , instead activated by cytokines at sites of tissue damage
What are the roles of the NK cells in innate response
Large granular lymphocyte= contain azurophilic granules, not bear T cell receptor or cell surface Ig.
Kill without previous sensization— lyse tumor cells, lyse virally infected cell, secrete cytokines
What are the roles of plasma proteins in innate response
Has a role in complement system
Mannose-binding lectin
C-reactive protein.
Types of adaptive immunity
Humoral
Cellular
Humoral immunity
Protects against extra cellular microbes and their toxins
Mediated B lymphocytes— Ig
Cellular Immunity
Defense against intracellular microbes and against cancers
Mediated by T Lymphocytes
What are the examples of Lymphocytes
Mature: not encountered with ag — naive
Effector: eliminate microbes
Memory: live in an state of awareness
CD8 T cell, B cell,Regulatory T cell, CD4 T cell
B and T cells are concentrated in
B— follicles, germinal center
T— paracortex
What are the types of T lymphocytes
Helper T lymphocytes— stimulate B to make ab and activate other leukocytes to destroy microbes.
Cytotoxic killer T lymphocytes — kill infected cells
Regulatory T lymphocytes — limit immune responses and present reactions against self ag.
How does T cell recognizes ag
By specific T-cell receptor (TCR)
What is the importance of CD4 and CD8
Required to initiate signals that activate T cells
Expressed on alpha beta T cells
What is the importance of CD4+T cell
Conductor of the immune system by secreting solvable factors— cytokines
What is the importance of TCR and features of it
Has 2 subunits alphabeta and gammasigma
Has a CD3 complex which TCR binds to this complex and to zeta chains
ALL OF THE CD3 ARE IDENTICAL — do not contribute to the specificity.
What are the units of T Cell Receptor Complex
CD3
Zeta chains
Alphabeta/ gammasigma
Alphabeta TCR
Recognize ag that are displayed by major histocompatibilty complex (MHC) of ag presenting cells.
Gammasigma TCR
Recognize peptides, lipids, small mol. Without MHC
Tend to aggregate at epi. Surfaces
Protection against microbes that try to enter through epi.
What are the featıures of B lymphocytes
Capable of producing ab
Ig synthesis and secretion
Present in LN, spleen, tonsil
How does the recognition of B cells occur
By B CELL AG RECEPTOR COMPLEX
Composed of IgM or IgD
CD21 is the receptor
Has unique ag specificity, derived from somatic rearrangement of Ig genes.
Features of macrophages
Phagocyte microbe and protein ag — innate immunity
Process ag and present peptide fragments to T cells— ag presentation
In cellular immunity— T cells activate macrophages and enhance ability to kill ingested microbes
In humoral immunity— phagocytes microbes that opsonized by IgG or C3b
Features of dendritic cells
Interdigitating DCs= under epi., most important ag-presenting cells for initiating T cell responses against protein ag.
Follicular DCs= in the germinal centers of lymphoid follicles in spleen, LN , production of humoral immune response
Lymphoid organs
Generative= thymus, bone marrow
Peripheral= LN,spleen,mucosal and cutaneous lymphoid tissues
Histocompatibilty molecules types
MHC 1= on all nucleated cells and platelet. Bind and display peptides that derived from proteins, CD8+ Cytotoxic Tcells can recognize viral or other peptides only if presented by these.
MHC 2= lonely restricted to ag- presenting cell. Present exo.ag , CD4 + helper T cells can recognize ag only if presented as a complex with class 2 mol.
