BIOL 620 Exam 1

Who is the father of immunology?

Edward Jenner

What is the milkmaid observation?

dairymaids didn’t die from smallpox as much as other people

Who is Louis Pasteur

attenuated pathogens can be used to build immunity against normal pathogens

What did Louis Pasteur study?

Anthrax in sheep

How did Pasteur popularize immunology?

1885 boy bitten by rabid dog and treated with attenuated rabies virus

What is immunology?

is the study of the cells and tissues that mediate
immunity and the investigation of the genes and proteins
underlying their function.

What is immunity?

from the Latin, immunitas “to be exempt from”

What can the immune system be activated against?

foreign substances, altered self molecules/cells or unfortunately even unaltered “self” molecules/cells

What is homeostasis?

a natural state of balance of all organs and the nervous and circulatory systems

What is infection?

the attachment and entry of a pathogen into the host

What is an extracellular pathogen?

pathogens that do not need to enter cells to reproduce

What are examples of extracellular pathogens?

some bacteria, most parasites, fungi

What is an intracellular pathogen?

pathogens that must enter a host cell in order to reproduce (usually via subverting the host’s endogenous processes

What are examples of intracellular pathogens?

viruses, some bacteria, few parasites

What are the 2 mechanisms underlying the immune response?

Cell-mediated immunity and humoral immunity

What is cell-mediated immunity?

depends on the action of cells that destroy or remove unwanted material from the body.

What is humoral immunity?

depends on soluble molecules in the serum of the blood that could eliminate foreign entities

What is an example of humoral immunity?

antibodies

What is an example of both mechanisms of immune response working together?

leukocytes produce cytokines (a signaling molecule)

What are the two types of immune responses?

innate and adaptive

What triggers innate immunity?

recognition of PAMPs and DAMPs

What is a PAMP?

pathogen-associated molecular pattern - a molecular structure on the surfaces of pathogens or cells they have infected

What is a DAMP

damage-associated molecular pattern - host macromolecules that exist when cells are damaged or dying

What are PRMs?

pattern recognition molecules

What are PRMs’ functions?

host proteins expressed by innate leukocytes that recognize PAMPs and DAMPs

Describe memory associated with PRMs

there is no memory - speed and strength of reaction is exact same each time

How is the adaptive immune system triggered?

antigens bind to antigen receptors (with specific recognition)

Describe memory associated with antigen receptors

adaptive leukocytes have memory - speed and strength of adaptive response is increased upon subsequent exposures

What are central elements of innate immunity?

barrier defenses, complement activation, phagocytosis, pattern recognition, inflammation, and target cell lysis

What are barrier defenses?

anatomical (skin), physiological (tears, low pH of stomach acid, vaginal lactic acid)

What is complement activation?

a complex system of enzymes that circulates in the blood in an inactive state

What is phagocytosis?

sophisticated means of engulfing entities - involved in antigen presentation

What are phagocytes?

PRR cells (neutrophils, macrophages, and dendritic cells) that perform phagocytosis

What is pattern recognition?

relies on PRRs to recognize DAMPs and PAMPs

What is inflammation?

PRRs engaged →pro-inflammatory cytokines are produced → localized gathering of cells and molecules necessary to repair tissue damage and clear pathogens

What is target cell lysis?

when cancer cells and cells with intracellular pathogens express DAMPs/PAMPs → target cells are lysed

Which cells carry out target cell lysis?

neutrophils, macrophages, and natural killer cells

What cells are involved in adaptive immunity?

Lymphocytes (B and T cells)

What are characteristics of adaptive immune response?

specificity, division of labor, memory, diversity, tolerance

Specificity

antigen receptors on surfaces of T (TCR) and B (BCR) lymphocytes hinge on the presence of unique molecular shapes of individual pathogens

What types of pathogens do B cells fight and how?

extracellular - antibody mediated clearance

What types of pathogens do Tc cells fight and how?

intracellular - lysis of infected host cells → prevent spread

What types of pathogens do Th cells fight and how?

intracellular and extracellular - secrete cytokines for activation of B and Tc cells and stimulation of innate leukocytes

What is immunological memory?

Enhanced adaptive response mounted upon second and subsequent exposures to pathogens so that signs of clinical illness are mitigated or prevented

What is clonal selection?

only lymphocytes bearing receptors specific for a particular antigen are triggered to respond to a stimulus

What is diversity?

innate immune system has limited capacity for antigen recognition, but adaptive system is limitless

What is the main genetic mechanism that allows wide diversity of adaptive immunity’s response?

somatic recombination - single, random combination of gene segments created in each developing lymphocyte

What does diversity guarantee?

There will be at least one clone expressing a unique receptor sequence for every antigen encountered during host’s life span

What is tolerance?

dealing with lymphocytes and recognizing “self antigens”

What is central tolerance?

eliminates lymphocytes that recognize “self antigens” early in development

What is peripheral tolerance?

functionally silences any lymphocytes that recognize “self antigens” that escaped central tolerance

What is primary immunodeficiency?

an affected individual is born with a genetic defect that impairs his/her ability
to mount innate and/or adaptive immune responses

What is acquired immunodeficiency?

An external factor such as a nutritional imbalance or pathogen may cause the loss of an immune system component.

What is transplant rejection?

the normal attack of a healthy immune system on a foreign tissue transplant meant to preserve life

What is an autoimmune disease?

when the tolerance of an individual's adaptive immune response fails, self tissues are attacked

What is a hypersensitivity?

an immune response that is too strong or long. When an individual’s normal adaptive immune system responds inappropriately to an antigen that is generally harmless, the immune response is manifested clinically as an allergy

What is chronic inflammation?

normal regulation of the inflammatory response is lost and is conducive to the formation of tumors, heart disease or autoimmune diseases

What is hematopoiesis?

The generation of all red and white blood cells

What are hematopoietic stem cells (HSCs)?

multipotent stem cells that create 2 distinct lineages

What are the 2 lineages of cells that arise from HSCs?

myeloid and lymphoid

When are HSCs detected after conception?

3-4 weeks

Where are HSCs found in fetuses?

liver, tibia, femur

Where are HSCs found in adults

axial skeleton: sternum, ribs, vertabrae, pelvis, and skull

Which 3 types of cells are granulocytes in the myeloid lineage?

neutrophils, basophils, and eosinophils

What are granulocytes

they are cells with intracellular granules

What 2 types of cells do not possess granules and use other means to carry out their functions?

monocytes and macrophages

Which cells compose the innate immune system?

granulocytes, monocytes, mast cells, and macrophages

What are the most abundant leukocytes in circulation and constitute majority of cells activated during an inflammatory response?

neutrophils

How many neutrophils in an average adult

over 50 billion

How long is the life-span of a neutrophil?

1-2 days - require constant production by bone marrow

How quickly can neutrophils respond to chemokine gradients?

as early as 30 minutes

What are the functions of neutrophils?

phagocytosis (PRRs of neutrophils bind to DAMPs or PAMPs) → degranulation → pus

What are basophils named for?

dark blue color when stained with hematoxykin

What is the population of leukocytes in the body like?

Present in very low numbers (less than 1% of all leukocytes - reside primarily in blood)

What do basophil granules contain?

substances to sustain inflammatory response

What are the functions of basophils?

Mainly degranulation, some rare phagocytosis

What are eosinophils named for?

the red color the exhibit when dyed with acidic dyes like eosin

What do eosinophil granules contain

highly basic proteins and enzymes that can kill large parasites

Where do eosinophils reside?

connective tissues (4% of all leukocytes)

What is the function of an eosinophil?

degranulation

What are some of the largest cells in the blood circulation?

monocytes

What are the main functions of monocytes?

phagocytosis, secretion of cytokines that promote and regulate inflammation

What do monocytes do in their day to day lives?

patrol blood for 1 day then enter tissues where they can differentiate into macrophages or dendritic cells (DCs)

What cells are several times larger than monocytes?

macrophages

where do macrophages reside?

various tissues around the body

What are kupffer cells?

liver macrophages

What are osteoclasts?

bone macrophages

What are littoral cells?

macrophages in the spleen

How long do macrophages live?

2-4 months

what do macrophages do?

phagocytosis of pathogens and spent cells and secretion of cytokines

What are hperactivated cells?

activated T cells that secrete cytokines that give macrophages additional properties

Can macrophages activate naive T cells?

No

What types of cells are in the lymphoid lineage?

T, B, Natural Killer, and Dendritic cells

What do T and B cells use to recognize pathogens?

Cluster of Differentiation markers (cell surface proteins)

What is cross-reacting

an antigen may be recognized by more than 1 lymphocyte if the shape and property is similar

What can lead to lymphocyte priming?

binding of a specific antigen → activation of a lymphocyte → cell division

What happens after lymphocyte priming?

progeny cells → morphological and functional changes → lymphoblasts within 18-24 hours after antigen perception → effector cells (short lived) and memory cells (long-lived)

What are effector cells of B cells?

plasma cells - secrete antibodies

What are effector cells of Tc cells?

Cytotoxic T Cells (CTL) - target cell cytolysis and cytotoxic cytokine secretion

What are effector cells of Th cells?

effector Th cell - secretes copious cytokines supporting B and Tc responses