Basics Flashcards
What is the one thing the body cannot recognize?
Prions
3 reactions of leukocytes
Phagocytosis, Cytotoxicity, Synthesis of soluble factors
Phagocytosis
Process of ingesting and enzymatically digesting particulate antigens
Cytotoxicity
Induction or lysis and/or apoptosis in tumor cells, mismatched tissue grafts, microbe-infected host cells
Innate immunity
all host defenses that are present and functional at birth
Adaptive immunity
Developed slowly in response to host contact with specific antigen
Natural barriers of innate immunity
Skin, mucous membranes, enzymes, pH extremes, sneezing
Components of Adaptive Immunity
B/T lymphocytes, antibodies/immunoglobulins, plasma cells
Immunological memory
Characteristic of the adaptive immune system. Is the increase in speed and strength with which B and T lymphocytes response to antigen upon re-exposure to the same antigen.
Clonal Selection Theory
A given antigen will induce proliferation and differentiation only of those B/T lymphocytes will have specific specific for that antigen
Humoral Immunity
Mediated by soluble proteins and glycoproteins present in the serum and extracellular tissue fluids. Consists of antibodies, complement, and C-reactive proteins.
Cell-mediated Immunity
Responsible for elimination of intra/extracellular pathogens, tumors, damaged host cells.
Types of WBC phagocytes
Neutrophils
Monocytes/macrophages
Eosinophils
Types of Granulocytes
Neutrophils
Eosinophils
Basophils
Mast Cells
Types of Cytotoxic cells
Natural killer cells
Cytotoxic cells
Opsonins
Antibody, complement components C3B and CRP. Coats bacteria and other particulate antigens to aid their recognition and ingestion by phagocytes. Opsonins take down the capsule’s protection against phagocytosis
Myeloid lineage Cells
Erythrocytes, Megakaryocytes, Polymorphonuclear granulocytes, Mononuclear phagocytes, dendritic cells
Lymphoid lineage Cells
B/T cells, NK cells, NKT cells, Innate lymphoid cells
What reverses anemia by restoring erythrocytes/RBCs?
Erythropoietin (Epotein, EPO)
What helps with recovery of PMNs only?
Granulocyte colony-stimulating factor (G-CSF). AKA Filgrastim
What helps with recovery of bone marrow PMNs, monocytes, and macrophages?
Granulocyte-monocyte colony-stimulating factor (GM-CSF). AKA Sargramostim
What 2 recombinant cytokines are used to reverse thrombocytopenia?
Interleukins-11 (Oprelvekin) and Thrombopoietin (TPO).
B lymphocytes
CD 19, 20, 21
Secrete antibodies, aiding in humoral immunity
Develop in the bone marrow
What CD marker do all T lymphocytes have?
CD3 and TCR
Helper T cells
CD4
Promotes immunity thru cytosine secretion (boss of immunity)
Regulatory T cells
CD4, 25
Prevents autoimmunity thru cytokine secretion
Cytotoxic T cells
CD 8
Kills infected cells/tumors/graft cells
Natural killer cells
CD 16, 56
Kills infected cells/tumors/graft cells
Natural killer T cells
CD 16, 56, TCR, NK1.1
Protects against microbial invasion thru the gut
Part of innate immune system
Innate lymphoid cells
No CD markers.
Protects mucosa from infection. Can contribute to mucosal inflammation
What does the T cell antigen receptor (TCR) do?
Binds to the antigen
What CD mediates signal transduction in T cells?
CD3
What antibodies does NK cells collaborate with during antibody-dependent cell-mediated cytotoxicity?
IgG
What is the difference between monocytes and macrophages?
Monocytes circulate in the blood until they reach the tissue they will inhabit, then they differentiate into macrophages
Process of phagocytosis?
Extension of pseudopodia, formation of phagosome, enzymes destroy the peptidoglycan of the bacterial wall, reactive oxygen species damage proteins/DNA
Antigen processing
The destruction of bacterium inside of the phagolysosome
Major histocompatibility molecules (MHC)
Proteins produced by macrophages. Placed on the surface of macrophages. Interact with TCR of T-cells
Antigen-presenting cells (APCs)
When macrophages present a MHC on the surface of their cell
Dendritic cells
Found under the epithelia and in most organs. Called Langerhans cells in skin. Most effective APCs. Necessary for activating naive T cells
Characteristics of granulocytes
Short-lived, multi-lobed nucleus, rich in enzymes, produce reactive oxygen species
Neutrophil
Purple, kills extracellular bacteria, make up 60% of WBCs, Receptors for IgG
Eosinophils
Red staining, kill worms, participate in immediate hypersensitivity reactions, receptors for IgE
Basophils
Purple-black staining, kill worms, Participate in immediate hypersensitivity reactions, good source of histamine, receptors for IgE
Mast Cells
Purple staining, kill worms, participate in hypersensitivity reactions, major source if histamine, tissue-fixed, long-lived, receptors for IgE, major contributor for Hay fever reaction
Megakaryocytes
Large cell with lobulated nucleus found in bone marrow, gives rise to platelets after cell bursts
Platelets
Enucleate cells that promote blood clotting and inflammation. Binds to collagen exposed on damaged endothelial cells, forming microthrombi
Rough range of normal WBC count
4800-11000/µL
Primary lymphoid organs
Bone marrow/Thymus. Where T/B lymphocytes 1st begin expression of antigen receptor
Secondary lymphoid organs
Where lymphocytes respond to antigens (clonal selection/proliferation)
Spleen, lymph nodes, mucosa-associated lymphoid tissue (MALT)
Hematopoietic stem cells
Express CD34 and stem cell antigen-1 (SCA-1). used for transplantation and immune reconstruction
Developmental stages of B cell
Stem cell→Pro-B cell→Pre-B cell→Immature B cell→Mature B cell→Memory or plasma cell
DiGeorge syndrome
Chromosome 22 deletion that results in little to no thymus. Few to no functional T cells→CD3 deficient. Commonly have hypocalcimic toxicity tetany post-delivery
Subcapsular region of thymus
Double negative thymocytes. NO CD4 or 8, or TCR
Cortex of the thymus
Double-positive T cell precursors. Express CD4/8 and TCR
Medulla of the thymus
Contains mature, single-positive T cells that express EITHER CD4 or 8, plus TCR and CD3. Contains Hassall’s corpuscles
Hassall’s corpuscles
In the medulla of the thymus. Play a role in dendritic cell/regulatory T cell differentiation
Where are the antigens that lymph nodes primarily responding to entering the body?
Skin and subcutaneous tissue
Functions of lymph nodes
Survey the lymph by macrophages, storage of B/T cells, antibody production
Functions of the lymphatic system
Maintain pressure/volume of interstitial fluid and blood. Isolate infectious agents and cellular debris
Anatomical compartments of the lymph node
Cortex, Paracortex, medulla
Cortex of the lymph node
1º follicles contain naive B cells. 2º follicles contain germinal centers with B cells undergoing mitosis in response to antigen stimulation
Paracortex
T cell area. Lymphocytes enter via high endothelial venules. Becomes enlarged during extreme cellular immune responses. Poorly developed in DiGeorge syndrome
High endothelial Venules
Contain specialized cuboidal cells that express adhesion molecules in high density and allow lymphocytes to bind tightly to the venue wall
Medulla of Lymph nodes
Cords: closely packed lymphocytes/plasma cells
Sinuses: contain macrophages and communicate with efferent lymphatics
Spleen
Major organ where antibodies are synthesized. Responds 1º to blood-borne antigens. In ULQ of abdomen
Infections commonly found in pts without a spleen
Pneumonia, Influenza, Salmonella, Neisseria
White pulp of spleen
Lymphocyte-rich regions. Periarteriolar lymphoid sheath and B cell rich follicles
Where are the T cells found in the white pulp of the spleen?
PALS (periarteriolar lymphoid sheaths)
Red pulp of the spleen
Contains plasma cells, resident macrophages, erythrocytes, platelets, granulocytes, lymphocytes. HEMOCATHERSIS. Recycled iron stored here
Hemocatheresis
Destruction of aged platelets and erythrocytes
Mucosa-associated lymphoid tissue (MALT)
Responds primarily to antigens that enter the body via mucosal surfaces. >50% of body’s lymphoid tissue.
What do B lymphocytes in the MALT produce?
Secretory IgA
Peter’s patches
Loose clusters of lymphoid tissue found in the small intestine.
M cells
epithelial cells that cover Peyer’s patches. Specialized for transcytosis of antigens from the lime not the sub epithelial T cells.
