Diseases of Immunity - Part 1 Flashcards
What is innate immunity?
Pre-existing defense against pathogens
What are the components of innate immunity?
Barriers
Complement proteins
Neutrophils, NK cells, Dendritic cells
What is adaptive immunity?
Specific, programmed defense to an antigen
What are the components of adaptive immunity?
Lymphocytes and Antibodies
What are some barriers involved with innate immunity?
Skin Mucous membranes Ciliated epithelia Tears Saliva Acid of the stomach
What are pattern recognition receptors?
Receptors that recognize common microbe components
What are 3 types of pattern recognition receptors?
Toll-like receptors
Nod-like receptors
C-type lectin receptors
What transcription factors to TLRs activate?
NF-KB
IRFs
Job of TLRs?
Increase cytokines and adhesion molecules
What do Nod-like receptors recognize and where are they?
In cytoplasm; recognize damaged cell products
ATP, uric acid
Job of Nod-like receptors?
Activate inflammasome which activates IL-1
What do C-type lectin receptors recognize and where are they?
Plasma membrane; recognize fungi
What complement protein is deposited on microbe?
C3b
3 jobs of complement activation?
MAC formation - lysis of microbe
Phagocytosis of microbe
+C3a/C5a - recruitment of leukocytes and inflammation
What controls NK cell activity?
Its receptors
What ligands can inhibit NK cells?
Self MHC molecules
Class 1 MHC
What ligands can activate NK cells?
Damaged cells recognized by NKG2D receptors
What are the generative organs for adaptive immunity?
Bone marrow
Thymus
What occurs at the bone marrow for adaptive immunity?
Generate lymphocyte stem cells and mature B lymphocytes
What cells will you find in the bone marrow?
Erythroid RBC precursors Megakaryocytes (platelet precursors) Neutrophils Adipocytes Endothelium
What occurs at the thymus for adaptive immunity?
T lymphocyte maturation
Describe T cell migration through the thymus
Immature T cells begin at peripheral cortex
As they mature they reach the central medulla
What does the medulla of the thymus contain?
Mature T cells Dendritic APCs with high levels of MCH classes 1 and 2 Hassall corpuscles (squamous cell nests)
What are the peripheral organs of adaptive immunity?
Lymph nodes
Spleen
Mucosal - associated lymph tissues (tonsils, adenoids, peyer’s patches)
What do lymphocytes interact with in lymph nodes?
APCs and antigens in circulating lymph
In lymph nodes, where are the T and B cells located?
T cells = paracortex
B cells = germinal center
What occurs at the lymph nodes?
T and B cell clonal expansion
B cell differentiation into plasma cells
Migrations of T and plasma cells into circulation
What do lymphocytes encounter in the spleen?
Blood-borne antigens
What purpose do mucosal - associated lymphoid tissues have?
Allow lymphocytes to be in close proximity to antigens in mouth and GI tract
CD4+
Helper T cells
Actions of CD4+ helper T cells?
Inflammation
Activation of macrophages and other lymphocytes
What class and antigen type do CD4+ helper T cells recognize?
MHC class 2 - Extracellular bacteria and allergens in APCs
Process of MHC class 2 cells displaying Ag?
- Endolysosomal enzymes take Ag -> peptides
- Peptides put into vesicle with MHC 2
- Both sent to surface for display
CD8+
Cytotoxic T cells
Actions of CD8+ cytotoxic T cells?
Killing of infected cells
What class and antigen type do CD8+ cytotoxic T cells recognize?
MHC class 1 - Intracellular viral and tumor antigens in NUCLEATED cells
Process of MHC class 1 cells displaying Ag?
- Proteosome takes Ag -> peptides
- Peptides taken to ER and bound to MHC 1
- Both sent to surface for display
What are MHC?
Peptide display for T cells
HLA
Describe Cell-mediated immunity
APCs bring back pathogens for T cell recognition
- T cells proliferate, differentiate, migrate and kill
Describe Humoral immunity
- B lymphocyte
- Become plasma cells
- Produce antibodies
= Neutralize, phagocytize microbe and activate complement
What T cells can help mature B cells?
CD4+
T cell dependent humoral immunity helps do what 2 things?
Isotype switching
Increasing affinity
IgM
1st Ab produced and is big pentamer
IgG
Longest 1/2 life and important in fetal protection
IgA
Mucosal defense and present in high levels of clostrum
IgE
Shortest 1/2 life and regulates hypersensitivity reactions
Which Ab has a high affinity for Fc receptors on mast cells, basophils and eosinophils?
IgE
Mucosal defense Ab thats in clostrum?
IgA
Fetal protection Ab?
IgG
1st Ab produced?
IgM
If lymphocytes are targeted against a pathogenic antigen, what happens to them?
Activated and cloned!
If there is a large population of immune cells with SAME genes, what could that indicate?
Neoplasia
Lymphoma
Abnormal clone
