HDM 2024 TBL1_Introduction to the Immune System_Khadka Final

The complement system.

Red pulp and white pulp.

Gut-Associated Lymphoid Tissue.

Nasopharyngeal-associated lymphoid tissue.

By secreting cytokines.

They work side by side through a feedback mechanism.

A system of interacting proteins produced by the liver that circulate in the blood.

They die and form pus.

T cells.

Blood, Lymph, and Lymph Nodes (LNs).

Normal flora refers to the microorganisms that are naturally present in various parts of the body.

Escherichia coli and Clostridium difficile.

Complement System, Acute Inflammatory response, Phagocytosis, and Fever.

By binding to them and neutralizing their effects.

During allergic responses and infections with helminthic parasites.

It leads to grossly impaired phagocyte function and increased susceptibility to infections.

Granzyme and perforin.

B and T cells, some macrophages, and dendritic cells (DCs).

They function as a 'bridge' between innate and adaptive immune responses.

They are a major component of pus.

By squeezing out through blood vessel walls in response to chemical signals (Chemotaxis).

To serve as an outer barrier composed of densely packed squamous epithelial cells and impenetrable keratinized cells.

C3a and C5a.

Perforin forms pores in the target cell, allowing granzyme to enter and induce apoptosis.

Sites where naïve adaptive immune cells interact with antigens and get activated.

Cromolyn and Diphenhydramine.

Drains and cleans excess interstitial fluid (ISF) to maintain fluid balance and returns it to the cardiovascular system.

PolyMorphonuclear Neutrophilic Leukocytes (PMNs).

Leukocytes.

Propionibacterium and Staphylococcus epidermidis.

A condition caused by defects in lysosomal trafficking regulator (LYST), affecting phagocyte function.

It opsonizes pathogens, aiding in phagocytosis.

A mechanism in the respiratory tract that helps remove microbes through the action of cilia and mucus.

They keep immunological memory of the antigen and differentiate into effector T cells upon re-encountering the antigen.

Binds targets using FcɛRI and antibodies IgE or IgG, then kills targets by releasing cytotoxic proteins and cytokines.

M Φ.

Phagocytic killing, antigen processing and presentation, co-stimulation, and cytokine delivery.

They respond more quickly and robustly, known as an anamnestic reaction.

The principle of immunological memory and the secondary antibody response.

T cells and dendritic cells (DCs).

Large-eaters or histiocytes.

It is involved in binding antigen and is a receptor for EBV.

They are the first cells to encounter antigens that enter the skin, lymph nodes, spleen, or liver.

They are the first to respond and are a hallmark of acute inflammation.

The entry of foreign bacteria (antigens) or tissue damage.

Smooth muscles, respiratory pump, and skeletal muscle pump.

It is critically involved in lysosomal transport and vesicle formation during phagocytosis.

A rapid response to tissue injury or infection that involves the recruitment of immune cells.

The process of lysis and death of target cells, facilitated by the membrane attack complex (C5b, C6-C9).

In the lower left quadrant of the abdomen.

To secrete cytokines that help with immune response against various pathogens and function as antigen-presenting cells (APCs).

The process of development of blood elements from hematopoietic stem cells.

~ 8 liters.

The necessary secondary signal delivered by co-stimulatory molecules to help activate T cells.

Neutrophilia indicates an increased number of neutrophils, while neutropenia indicates a decreased number, leading to increased susceptibility to infections.

A common lymphoid precursor (CLP).

Developmental origin, cytological appearance, location, and immune functions.

They line the digestive, respiratory, and urogenital tracts, secreting mucus that helps trap microbes and aids in their mechanical removal.

Glycoproteins, proteoglycans, and protective enzymes.

The process by which certain immune cells engulf and digest pathogens or debris.

Drainage of excess interstitial fluid (ISF).

Cells like dendritic cells and macrophages that present epitopes on their surface after phagocytosis.

They secrete cytokines that shape immune responses by enhancing or suppressing immune cell functions.

They are less organized compared to secondary immune organs.

Removing senescent RBC, storing RBC, WBC, and platelets, and mounting immune responses against blood-borne antigens.

~60%.

To recognize and destroy invading antigens and neoplastic cells, and alert other immune cells.

Fluid from the blood seeps out of capillaries into the tissues, creating interstitial fluid.

They filter lymphatic fluid and activate adaptive immune cells if antigens are present.

Plasma, platelets, and cells (RBC, WBC).

Repeated exposure to allergens, which are often polyvalent.

A mechanism where NK cells use Fc Ƴ III receptors to bind antibody-coated antigens on infected or cancer cells.

They function as intercellular mediators or signaling molecules.

Mast cells and macrophages.

In blood serum, tissue fluids, and mucosal surfaces.

Elimination of virally-infected and neoplastic (cancer/tumor) cells.

ECF that surrounds cells in the tissues, facilitating the transfer of nutrients and wastes to/from cells and capillaries.

Oxidative and non-oxidative killing mechanisms.

Neutrophilia.

A secondary antibody response shows significantly increased levels of antibodies compared to the primary response.

A genetic disorder affecting granulopoiesis, leading to neutropenia.

Red blood cell (RBC).

Filter lymphatic fluid transported via lymphatic vessels.

Antibodies specific to the antigens.

Memory B cells and Plasma B cells.

In tissues and secondary immune organs.

Failure of either the innate or adaptive immune divisions, especially failure in innate immunity.

The process of coating antigens with host proteins to enhance phagocytosis.

Aggregates of lymphoid tissue found in the small intestine.

To phagocytose pathogens and kill them intracellularly.

Blood.

They enhance the overall immune response.

Through granulopoiesis at a rate of 5 × 10^10 per day.

Humoral immunity, production of antibodies, and keeping immunological memory.

Intracellular, oxidative, and non-oxidative mechanisms.

Through degranulation and neutrophil extracellular traps (NETs).

Blood, Lymph, and Lymph Nodes (LNs).

T lymphocytes (T cells), B lymphocytes (B cells), and Natural Killer (NK) cells.

On the skin, eyes, GI tract, outer ear, nose, mouth, throat, urethra, and vagina.

B cells.

To collect excess interstitial fluid from tissues and return it as lymphatic fluid to the blood vasculature.

Redness, warmth, pain, swelling, altered function.

A host defense mechanism to infectious disease, especially bacterial infections.

The temperature-regulation center in the brain normally holds at 37°C but raises during infection.

They are inactive when intact and become active when fragmented.

Lactobacillus spp. and Candida albicans.

In the dermis and lamina propria.

Cellular immunity, secretion of cytokines, and elimination of cancer cells and virally infected host cells.

Lymphoid-derived lineages.

Pyrogens produced exogenously by infecting microbes and endogenously by macrophages and monocytes.

It helps to enhance the ability of antibodies and phagocytic cells to clear pathogens.

The uptake of pathogens by phagocytic cells leading to their destruction.

Cytotoxic killing through degranulation and ADCC.

A common myeloid precursor (CMP).

Hematopoietic stem cells (HSC).

Repeated exposure to the same antigen.

Intracellular antigens.

It enables elimination of pathogens before the host becomes symptomatic, providing immunity.

They block infection and help defend by colonizing barriers.

Microfold cells (M cells).

T helper (Th) cells and Cytotoxic T (Tc) cells (or Cytotoxic T lymphocytes, CTLs).

The process of development of T cells.

20-50% (approximately 45% T, 40% B, and 15% NK).

Lactic acid, resulting in a vaginal pH of 3.8-4.5.

Yes, they can function as antigen-presenting cells (APCs), though less commonly than dendritic cells and macrophages.

Degranulation, releasing inflammatory mediators such as histamine.

It is sucked by lymphatic capillaries and transferred to collecting vessels, then filtered through draining lymph nodes.

Lymphocytes that function in innate immunity.

Perforin-granzyme mechanism.

Red bone marrow and thymus.

Red bone marrow (RBM).

A decreased number of neutrophils.

Megakaryocyte.

Life-threatening bacterial infections, especially those caused by Staphylococcus spp.

They differentiate into macrophages and dendritic cells.

B cells.

Flow cytometry and microscopy, using immunohistochemistry (IHC) and immunofluorescence (IF).

Polymorphonuclear with pink cytoplasmic granules.

They migrate through lymphatic vessels into systemic circulation.

It is involved in cell-cell adhesion.

Cytokines and chemokines.

A ring of lymphoid tissue formed by the palatine and adenoid tonsils.

Low pH, temperature, antimicrobial peptides, enzymes, acute phase proteins, cytokines, and complement proteins.

Blood, lymph, and lymph nodes.

1. Stimulate inflammatory response, 2. Opsonize pathogens for phagocytosis, 3. Form membrane attack complex for cytolysis.

Recurrent, life-threatening infections, neurological defects, and oculocutaneous albinism.

The formation and development of immune cells.

Inflammatory mediators including histamine and other cytokines.

They help with the activation of B cells in re-infection with the same antigen.

Viruses, by producing large amounts of type-I interferons (IFN-alpha, IFN-beta).

They kill host cells infected with viruses or intracellular bacteria, as well as cancer/tumor cells.

500-800.

It allows for antigens present in tissues to be delivered to secondary immune organs, aiding in the activation of T and B cells.

Innate immune cells such as granulocytes, phagocytes, and NK cells.

Neutrophils, Eosinophils, and Basophils.

They help defend the host when the first two lines are overpowered and keep a memory of the pathogen.

Diffuse or nodular aggregates of immune cells located in mucosal areas.

Bi-lobed nucleus with dark purple cytoplasmic granules.

Monocytes have a secondary role to neutrophils in eliminating pathogens.

They may have dendritic processes.

Serotonin, histamine, bradykinin, prostaglandins, leukotrienes, thromboxane.

Elimination of tumor/cancer cells and virally infected host cells.

Peristalsis, flushing of the urinary tract, and mucociliary clearance of the respiratory tract.

Eosinophilia.

Excessive nuclear segmentation and giant lysosomes in the cytoplasm.

Conventional (myeloid) dendritic cells (cDCs or mDCs) and plasmacytoid dendritic cells (pDCs).

Lymph nodes, spleen, and mucosal-associated lymphoid tissues (MALTs).

Because they play a crucial role in regulating immune responses through cytokine secretion.

A myeloid-derived lineage cell.

Across the gut wall.

Physical barriers, chemical and physiological barriers, and normal microbiota.

Y-shaped glycoproteins produced by activated B cells (plasma cells) in response to specific antigens.

To transport antigens.

Extracellular pathogens.

Pattern Recognition Receptors that recognize and bind PAMPs on pathogens.

Agranulocytes.

They act as Antigen-Presenting Cells (APCs).

Intracellular, oxidative, and non-oxidative mechanisms.

Tissue and lymph nodes.

They are involved in allergic disorders and the inflammatory response to parasitic infections.

It results in acute allergic reactions.

A process where antibodies assist in killing infected host cells.

Extracellular parasites, especially helminths.

Dendritic cells (DCs), B cells, and T cells.

Treatment with antiproliferative agents.

In open spaces formed between trabeculae of spongy bone in vertebrae, epiphyses of long bones, innominate bones of the pelvis, and flat bones of the skull, sternum, and ribs.

Small (1-2 cm), bean-shaped organs.

In the lamina propria of mucosal membranes lining the GI, respiratory, and urogenital tracts.

B cells and T cells.

Progenitor T cells (thymocytes), stromal cells, thymic epithelial cells, macrophages (M Φ), and dendritic cells (DCs).

Capsule and its extensions, trabeculae, which form partitions around lobules.

Red-orange.

Thymosin and thymic stromal lymphopoietin.

In low numbers in blood, mostly stored in bone marrow and spleen.

They are involved in the immune response within the colon.

Blood and tissue.

To recognize and bind to antigens, assisting with phagocytosis.

Infections caused by fungi, Gram-negative bacteria, and Gram-positive bacteria such as Staphylococcus and Streptococcus spp.

To create an unfavorable environment for pathogens and enhance immune function.

They limit the ability of mast cells and basophils to degranulate, preventing the release of histamine and related inflammatory mediators.

Neutrophil, eosinophil, basophil.

No, they do not function as APCs.

Immunological memory.

By facilitating the circulation of immune cells to secondary immune organs.

They keep immunological memory of the antigen and differentiate into effector B cells upon re-encountering the antigen.

Butterfly-shaped endocrine gland situated anterior to the heart.

Five: IgA, IgD, IgE, IgG, and IgM.

Within minutes to hours.

M1 (pro-inflammatory) and M2 (anti-inflammatory) cytokines.

They secrete anti-inflammatory cytokines and are involved in wound healing and tissue repair.

Extracellularly.

Lysozyme, Lactoferrin, Peroxidase.

Tissue.

It mediates the uptake of pathogens by phagocytic cells.

Via subclavian veins where it mixes with venous blood.

By bringing naïve T lymphocytes in contact with antigens, aiding in their activation and proliferation.

It is analogous to the lymph node, with immune cells arranged in nodules.

Cervical, Supraclavicular, Axillary, Popliteal, Femoral, Inguinal, Mesenteric, Supratrochlear, Mediastinal.

Adaptive immune responses (B and T cell activation) against antigens present in blood.

Surface glycoproteins that immune cells use to communicate and interact.

Granulocytes and Agranulocytes.

CD3, CD28, CD4, CD40L, CXCR4/CCR5.

Macrophages located in the liver.

It acts as a receptor for PAMPs and enhances phagocytosis.

Bronchus-associated lymphoid tissue.

Phagocytic killing, antigen processing and presentation, and cytokine production.

They kill bacteria, fungi, and enveloped viruses by disrupting their membranes.

Removes spent RBC, recycles iron, stores platelets, and stores blood for mobilization during hemorrhagic shock.

B cell lymphopoiesis.

B cells, T cells, and dendritic cells (DCs).

Mucosa-Associated Lymphoid Tissues.

Cluster of differentiation.

An antibody (Ab) or immunoglobulin (Ig).

Granulocytes (Neutrophils, Eosinophils, Basophils), Macrophages, Dendritic cells, and Natural Killer cells.

CD16 and CD56.

In the thymus.

Gut-associated lymphoid tissue.

Macrophages (M Φ) or dendritic cells (DCs).

In tears, phagocytes, saliva, and other secretions.

Degranulation; they release inflammatory mediators such as histamine and play a role in allergic responses.

Spontaneous organized lymphoid structures that arise in chronic inflammation, select cancers, and autoimmune diseases.

It is serviced by blood vessels but does not have afferent lymphatic vessels, hence does not drain lymphatic fluid.

Infants have a distinct distribution pattern compared to adults.

A myeloid-derived lineage cell involved in allergic responses.

Antigens present in interstitial fluid (ISF) drained from upstream tissues.

Adaptive immune cells, specifically B and T cells, and their products.

A dense outer cortex and a less dense inner medulla.

They secrete pro-inflammatory cytokines and activate the inflammatory response to infection and cancer.

Approximately 3.0.

Defensins.

Phagocytic and cytotoxic; they are the key first responders to infection and play a role in the elimination of bacteria and fungi.

Phagocytic and antigen presentation; they help mount the adaptive immune response and act as a bridge between innate and adaptive systems.

With rhG-CSF (recombinant human granulocyte colony-stimulating factor) to stimulate granulopoiesis.

The delivery of antigens to secondary immune organs.

They recognize and help destroy any pathogen that crosses the barriers.

40-75%.

Pathogens enter the body's soft tissues, stimulating innate immune responses.

Antibodies, mannose-binding lectin (MBL), C3b protein, C-reactive protein (C-RP).

Lymph nodes located in the mesentery that are part of the immune system.

Through degranulation and antibody-dependent cellular cytotoxicity (ADCC).

Phagocytic; they play a role in acute/chronic inflammation and can present antigens.

The use of antibodies directed against CDs to phenotype cells.

They traffic to the draining mesenteric lymph node to amplify the adaptive immune response.

In the bone marrow.

Humoral Immunity and Cellular Immunity.

Kidney bean-shaped nucleus with moderate cytoplasm.

Secretion of pro-inflammatory cytokines.

Blood.

Blood, lymph, lymph nodes, and tissue.

Sites for B and T cell activation and major sites for mounting adaptive immune responses.

B cell receptors (BCRs) and T cell receptors (TCRs).

Conjunctiva-associated lymphoid tissue.

Phagocytic cells that participate in the elimination of bacteria and fungi.

2-10%.

It contains lymphoid tissue and plays a role in immune function.

They are cytotoxic and play a role in the elimination of extracellular parasites and in allergic responses.

Foam cells and multinucleated giant cells.

5.0-5.5.

Phagocytic; they play a role in the elimination of bacteria and fungi and can present antigens.