NP4A

Question 1

proteins and glycoproteins associated with myelin for which we have autoreactive T cells

Answer 1

privileged antigens

Question 2

We also have cells that are non-renewable, mainly __________ , making cell loss during an inflammatory process problematic

Answer 2

neurons

Question 3

Helps create an environment conducive to neuronal conduction and myelin maintenance, keeping out small molecules that may serve as false neurotransmitters or those that might be toxic to oligodendrocytes. Can also help to exclude microorganisms that periodically find their way into the vascular system.

Answer 3

blood brain barrier

Question 4

The barrier does not prevent ____________ from entering.

Answer 4

immune cells

Question 5

__________ routinely enter and exit nervous tissue as part of their immune surveillance

Answer 5

Lymphocytes

Question 6

Tight junctions between endothelial cells can be broken, and the basement membrane modified, and this is particularly the case in an environment of ___________, in which case the barrier is transiently broken down

Answer 6

inflammation

Question 7

__________ and _______ can produce inflammatory cytokines that initiate the process, but it is microglia in particular that make this happen

Answer 7

Neurons , glia

Question 8

There are ____________ in the CNS as well, and this allows antigens of CNS origin to be processed by deep cervical lymph node

Answer 8

lymphatics

Question 9

How can we minimize damage to the CNS during the course of inflammation?

Answer 9

• limit expression of antigen presenting molecules
• you cannot prime an immune response in the CNS
• we have regulatory T cells in the CNS that can dampen certain immune responses
• lymphocytes (T cells) can eliminate intracellular pathogens in neurons without actually killing the cell

Question 10

Antigen presenting complexes:

Answer 10

MHC I
MHC II

Question 10

Antigen presenting complexes:

Answer 10

MHC I
MHC II

Question 11

would present to T cells responsible for cell mediated immunity

Answer 11

MHC I

Question 12

would present to lymphocytes ultimately that are driving humeral immune responses

Answer 12

MHC II

Question 13

No CNS resident cell expresses _______at basal levels, and _________ can only be induced in microglia when stimulated by interferons released from activated lymphocytes

Answer 13

MHC II

Question 14

Only microglia express ________ at basal levels, although interferons released from activated lymphocytes may induce _______ on astrocytes and oligodendrocytes – but not neurons

Answer 14

MHC I

Question 15

You cannot prime an immune response in the _______

Answer 15

CNS

Question 16

Priming is done by dendritic cells located in lymph nodes, and so priming immune responses to CNS antigens is no simple matter. You can only stimulate primed lymphocytes through antigen that is presented by ____

Answer 16

glia

Question 17

But there is a downside: neurons and oligodendrocytes (but particularly neurons) are a great place for intracellular pathogens such as viruses to _____

Answer 17

hide

Question 18

If the agent finds itself in the blood stream, it may invade the CNS through blood vessels penetrating from the _________or those located in the _________

Answer 18

meninges, choroid plexus

Question 19

If the agent is a virus, all you need to be able to do is infect endothelial cells (in meningeal vessels) or highjack a _______ that knows how to cross the blood-brain barrier

Answer 19

leukocyte

Question 20

____________ also enter by infecting the blood vessel lining

Answer 20

Protozoal

Question 21

_________ and ___________ use a blunt force approach – cause vasculitis, essentially destroying any barrier function

Answer 21

Bacteria, fungi

Question 22

Alternatively, you can infect a __________ process and this should be relatively easy to do if you infect the upper respiratory tract – hit those olfactory neurons and take a ride through the cribriform plate

Answer 22

peripheral nerve

Question 23

a portion of the ethmoid bone located at the base of the skull

Answer 23

cribriform plate

Question 24

(neutrophils) – think bacteria first

Answer 24

Suppurative
Example: suppurative meningitis

Question 25

(macrophages) – think fungal

Answer 25

Granulomatous
Example: granulomatous encephalitis

Protozoa also cause granulomatous inflammation, but this is only apparent microscopically unless they cause vascular damage with hemorrhage and/or tissue necrosis

Question 26

(fibrin) – think of an agent that damages vascular walls (e.g., some bacteria or an immune complex disease)

Answer 26

Fibrinous
Example: periventricular fibrinous encephalitis (cat with FIP)

Question 27

Those infiltrates that you won’t see grossly (unless associated with hemorrhage or necrosis)

Answer 27

Non-suppurative

Question 28

(lymphocytes, monocytes, and/or plasma cells) – think viral, protozoal, and parasitic infections. The latter may also be associated with eosinophilic infiltrates.

Answer 28

Non-suppurative

Question 29

comprised of leucocytes that accumulate in the perivascular space around post-capillary venules before their infiltration into the parenchyma of the central nervous system

Answer 29

perivascular cuff

Question 30

Viruses entering the bloodstream can find multiple ways of entering the brain, but we can survive these infections through adaptive immune (inflammatory) responses. Which of the following properly describes the host response?

Answer 30

Microglia present viral antigens to lymphocytes that have been primed in the periphery and those activated lymphocytes mediate viral clearance.

Question 31

The nature of the immune response in CNS allows you to survive an initial viral infection, but what are the potential collateral effects?

Answer 31

• virus might persist in neurons, where lack of MHC expression compromises immune surveillance
• prolonged inflammation may result in the presentation of privileged antigens with activation of autoreactive lymphocytes, ultimately causing immune-mediated disease