Infante - Immune response Flashcards
what is the primary function of the immune system?
to protect against pathogens (against infections) and against tumors (fight transformed cells)
What is immunity?
the ability to resist an infection caused by intra- and extracellular bacteria, parasites, viruses, or fungi
The immune system is composed of: - molecules - cells - organs/tissues. What belongs to each of these categories?
Molecules include: antibodies, complement, cytokines
Cells: lymphocytes, macrophages, granulocytes
organs/tissues: bone marrow, thymus, lymph nodes, spleen…
Primary lymphoid organs are…
where immune cells are produces
- bone marrow and thymus
Secondary lymphoid organs are…
sites of lymphocyte activation
-spleen, lymph nodes, and mucosal assoc lymphoid tissue: ex. gut assoc lymph tissue - tonsils, appendix, and Peyer’s patches
which of the following cells are involved in Natural/innate immunity?
A. Natural Killer cells B. Basophils C. Dendritic cells D. Mast cells E. B lymphocytes F. T lymphocytes
A. Natural Killer cells
B. Basophils
C. Dendritic cells
D. Mast cells
which of the following cells are involved in Specific/adaptive immunity?
A. Natural Killer cells B. Basophils C. Dendritic cells D. Mast cells E. B lymphocytes F. T lymphocytes
E. B lymphocytes
F. T lymphocytes
What are the features of Natural/innate immunity?
- cells have receptors with broad specificity
- cells recognize PAMPs - pathogen assoc molecular patterns
- not able to expand/proliferate
- immediate response
- do not lead to immunological memory
- pathogen receptors are encoded in the germline - PRR - pattern recognition receptors
What are the features of acquired/specific immunity?
- cells have receptors with narrow specificity
- pathogen recognized by receptors generated randomly: B-cell (BCR) and T-cell (TCR) receptors
- able to expand/proliferate
- slow (3-5 day) response
- leads to immunological memory
Why do we need Humoral immunity (B-cells)?
- are able to generate antibodies
- can bind to pathogens in an extracellular way
Why do we need Cell mediated immunity (T-cells)?
- need T-cells to attack intracellular microbes within an infected cell
- need cytotoxic T-cells to kill cells that have been infected intracellularly
What are PAMPS?
pathogen assoc molecular pattern molecules
- recognized by pattern recognition receptors (PRR)
- bearing cells of the innate immune response as well as many epithelial cells
What are DAMPS?
damage assoc molecular pattern molecules
-cells derived and initiate and perpetuate immunity in response to trauma, ischemia, and tissue damage
How are lymphocytes activated?
1st signal - antigen recognition
2nd signal - interaction with other cells
–> for T-cells - 2nd signal comes from APC (antigen presenting cell)
–> for B-cells - 2nd signal comes from TFh cells
MHC class II molecules are…
expressed principally on Antigen Presenting Cells, and present engulfed pathogens to Th cells
MCD II restricted means…
that T cells are only able to recognize antigens that are presented by MHC class II
MHC class I molecules are…
expressed on all nucleated cells, present pathogens of the cytosol (virus and other intracellular pathogens) to cytotoxic T cells
Health or disease is a balance between:
-pro-inflammatory and anti-inflammatory agents, as well as between - effector and regulatory agents
A. true
B. false
A. true
What does ‘Immune Privilege’ mean?
- tissue grafts can survive for extended periods of time
- essential for damage restriction during inflammation in the CNS
- is maintained by:
- the low expression levels of MHC class I and II
- the presence of the BBB
What was immune privilege found to be not maintained by?
- the lack of a specialized lymphatic drainage
- the absence of dendritic cells
There are several routes of leukocyte entry into the brain:
- brain parenchyma
- glia limitans
- perivascular space (containing CSF)
- parenchymal venule
What additional route of entry was discovered in 2010?
the choroid plexus
-via tight junctions and the blood-cerebrospinal fluid barrier (BCSFB)
There are 3 sites of immune cell entry into the CNS. What are they?
- through the choroid plexus
- through the perivascular or Virchow-Robin space
- through postcapillary venules (classical way, via BBB)
How do leukocytes and antigens leave the CNS?
- how do lymphocytes circulate in the healthy CNS?
via the:
- ciribiform plate -olfactory bulb. Moves the cell from CSF –> lymphatics
- and Arachnoid granulations. Moves cells from CSF –> blood circulation
What is the role of the meningeal lymphatics?
- enable the drainage of macromolecules and immune cells in the CSF to reach the deep cervical lymph node fluid –> sinuses
- role of specialized lymphatic drainage
From an immune perspective, pathology can be seen as:
an imbalance between pro vs. anti-inflammatory
an imbalance between neurotoxic vs. neurotrophic
Immune surveillance…
- is necessary in the CNS against infection and injury
- performed by T-cells
What are the 3 barriers that provide sites of Leukocyte entry into the CNS?
- blood-meningeal barrier (BMB)
- blood CSF barrier (BCSFB)
- blood brain barrier (BBB)
Lymphocytes do not interact with glia cells
A. True
B. False
B. False
How do Lymphocytes interact with neurons?
- via soluble factors (eg. cytokines)
- via MHC independent mechanisms
What is known about Myasthenia gravis (MG)?
- it is an antibody-mediated autoimmune disorder
- affects women aged 20-40
- it affects the neuromuscular junction
- target antigen is known (anti-Musk)
What is known about Guillain-Barre syndrome (GBS)?
- it is an antibody-mediated autoimmune disorder that affects peripheral neurons
- low prevalence
- target antigen is partly known
- etiology is partly described
What is known about Multiple Sclerosis (MS)?
- it is a T cell mediated autoimmune disease of the CNS (assumed to be CD4+ T cell mediated)
- onset between 20-40 years
- females 2x affected
- immune cells have to pass the BBB
- target antigen unknown
- etiology unclear
- animal model is Experimental Autoimmune Encephalo-myelitis (EAE)
Which of the following diseases are antibody-mediated autoimmune disorders? (more than one may be correct)
A. Myasthenia gravis (MG)
B.Guillain-Barre syndrome (GBS)
C. Multiple Sclerosis (MS)
A. Myasthenia gravis (MG)
B.Guillain-Barre syndrome (GBS)
What are the two types of T Lymphocytes?
- Helper T cells
- Cytotoxic T cells
What is a Helper T cell? (Function and phenotypic markers?)
Function:
- stimuli for B cell growth and differentiation
- Macrophage activation
- stimuli for eosinophils
- MHC class II restricted
Phenotypic markers:
-CD3+ CD4+ CD8-
What is a Cytotoxic T cell? (Function and phenotypic markers?)
Function:
- lysis of virus infected cells, tumor cells, allografts
- macrophage activation
- MHC class I restricted
Phenotypic markers:
-CD3+ CD4- CD8+
