lecture 5- hypersensitivity pt. 2

Question 1

what can lead to allergies

Answer 1

excessive hygiene, vaccination and overreliance on antibiotics reduces immune system’s experience

Question 2

basophils

Answer 2

thought to be the key cell initiating Th2 response
- due to their ability to make IL-4 and IL-13 at the start of the immune response
- can drive isotype switching to IgE and IgG4 through interaction with B cells through their CD40L

Question 3

name 2 lipid mediators

Answer 3

prostaglandins & leukotrienes

Question 4

describe lipid mediators

Answer 4

prostaglandins and leukotrienes make you feel bad during infection
- aspirin stops effects of prostaglandins through active prostaglandin synthase

Question 5

Type II is __ driven
Type III is __ driven
Type IV is __ driven

Answer 5

IgG
IgG
Th1

Question 6

describe type II hypersensitivity reactions

Answer 6

caused by small molecules that bind to cell surface molecules, changing their structure- perceived by the immune system as foreign
- antibody response develops, IgG
- upon antibody binding, leads to cells destruction by complement and phagocytosis & NK cells
- penicillin can induce this

Question 7

describe penicillin’s activity

Answer 7

B cell responses directed against penicillin antigens on erythrocyte- supported by Th2 response, will have IgE(mast cell degranulation) and IgG(macrophages, complement receptor-mediated uptake)
- penicillin alters erythrocytes and targets them for degradation through complement and macrophages

Question 8

blood group antigens and transfusions

Answer 8

transfusion can give rise to a life threatening type II hypersensitivity response
- the major immunogenetic barrier to transfusion is the structural polymorphisms of the carbohydrates decorating the erythrocyte surface
- antigenic differences in these molecules are ABO system

Question 9

describe type III hypersensitivity

Answer 9

initiated by immune complexes depositing on the walls of small blood vessels or alveoli – activates complement – inflammation and tissue damage
- change in immune complex size as immune response progresses
- arthus reaction or serum sickness

Question 10

type IV is referred to as ___

Answer 10

delayed type hypersensitivity (DTH)

Question 11

describe type IV hypersensitivity

Answer 11

caused by products of antigen-specific effector T cells(CD4 Th1 mediate the majority of these reactions- produces IFN-y)
- involve macrophages (T cells and macrophages and the cytokines they make)
- ex. of antigens = insect venom, mycobacterium
- local irritation 24-72 hrs after exposure

Question 12

granulomas

Answer 12

occur in lungs and lymph nodes of those infected with mycobacterium
- provides a mechanism for walling off infection from rest of body, walled off structure in muddle are macrophages infected with bacteria, infection controlled by T cells- all walled off by fibroblasts- keep it latent

Question 13

inflammation of the small intestine is caused by ___ responding to peptides derived from gluten

Answer 13

CD4 T cells