Immune Mediated Inflammation- Lesions of Hypersensitivity

Question 1

what are the 4 main types of immune-mediated inflammation?

Answer 1

1. Type 1: immediate- allergies
2. Type 2: cytotoxic
3. Type 3: immune complexes
4. Type 4: delayed-type hypersensitivity

Question 2

describe Type I reactions (4)

Answer 2

1. allergies, mediated antibody IgE
2. antigen cross-linking with membrane-bound IgE antibody causes histamine release from mast cells, which can cause tissue damage and infiltrations of eosinophils basophils
3. requires previous exposure to prime IgE!
4. examples include: hives, hay fever, and erythema reactions

Question 3

describe Type II reactions (3)

Answer 3

1. cytotoxic; mediated by antibody IgG IgM
2. antibody reacts directly with the antigen that is bound to the cell membrane to induce cell lysis through complement activation (the antigen may be intrinsic “self” (autoimmune rxns) or extrinsic “non-self”)
3. examples include: Rh incompatibility of newborns, blood transfusion reactions, and immune-mediated hemolytic anemia

Question 4

describe Type III reactions (4)

Answer 4

1. mediated by IgG and IgM-antibody complexes
2. antibodies bind antigen, forming antigen-antibody (immune) complexes that activate complement, resulting in neutrophil chemotaxis and activation (the body deposits these complexes somewhere it thinks is out of the way, but nothing is out of the way in the body)
3. neutrophils then release tissue damaging enzymes
4. examples include: lupus, feline infectious peritonitis

Question 5

describe Type IV reactions (4)

Answer 5

1. delayed; cell mediated (lymphocytes and macrophages)
2. interactions of antigens with the surface of lymphocytes causes sensitized lymphocytes to produce cytokines that result in tissue damage
3. this reaction takes at least 24-72 hours, or longer, after contact with the antigen to fully develop (takes time to prime T cells)
4. examples include: poison ivy or poison oak, inflammatory bowel disease

Question 6

adult male cat came in febrile with a large, warm, painful mass on mandible after a cat fight. a yellow exudate came out of the lesion

what substance does the lesion contain? what kind of necrosis? what kind of inflammatory cell type?

Answer 6

substance: pus
necrosis: liquefactive
inflammatory cell type: neutrophils, causing purulent inflammation

give antibiotics and neuter

Question 7

goat found with lesions indicating corynebacterium pseudotuberculosis infiltrated with macrophages and multi-nucleated giant cells.

what kind of necrosis?
what kind of inflammation?
goat was down because a mass was pressing on spinal cord; what type of necrosis in spinal cord?

Answer 7

necrosis: caseous
inflammation: granulomatous
necrosis in SPINAL cord: liquefactive due to lack of coagulability (would happen due to pressure from mass anywhere else; mass is not inside the spinal cord, is just pressing on it)

Question 8

kid stung by bee = problems breathing

lesion diagnosis from slide?
most likely reason for breathing problems?
dad says not allergic bc kid stung by bee before; what happening?
advice to parents?

Answer 8

lesion: focal serous dermatitis
breathing problems: Type I hypersensitivity = vasoconstriction
what happening: previous exposure to bee sting = prime IgE to go crazy
advice to parents: give this kid epi from now on

Question 9

man on hike gets contact dermatitis two days later.

what hypersensitivity?
why take 2 days?
why is lesion linear?
daughter who was with him has no lesions; why?

Answer 9

hypersensitivity: type 4
why 2 days: need time to recruit T lymphocytes and activate them to recruit cytokines and macrophages
why lesions roughly linear? pattern that he brushed the ivy in
why daughter no lesions? either no exposed or different MHC than dad

Question 10

cat with IMHA, yellow eyes and yellow skin.

what hypersensitivity?
possible pathogenesis?
name of clinical appearance?
cause of clinical appearance?

Answer 10

hypersensitivity: type 2; cytotoxic
possible pathogenesis: infection of RBCs = body kills and lyses them
name of clinical appearance: icterus/jaundice
cause of clinical appearance: increase in bilirubin from RBC destruction

Question 11

opened uterus from dog with pyometra and goo leaking out.

exudate?
name of inflammation of inner lining of uterus?
acute or chronic?

Answer 11

exudate: purulent
inflammation: endometritis
acute or chronic?: acute; do not see fibrous connective tissue = can not be chronic

Question 12

cat with feline infectious peritonitis

what exudate on surface of peritoneum and organs like the lungs?
what kind of hypersensitivity?
pathogenesis?

Answer 12

exudate: fibrinous