hypersensitivity reactions

what are the four hypersensitivity reactions

1. anaphylactic reactions

2. cytotoxic reactions

3. immune complex reactions

4. delayed cell mediated reactions

what are the 2 examples of anaphylactic reactions

1. allergic reactions

2. anaphylactic shock

descriptor

• occurs minutes after second exposure (already sensitized)

anaphylactic shock

descriptor

• antibody involved: IgE

anaphylactic reactions

steps of anaphylactic reactions

1. antigen + IgE on mast cell or basophil

2. degranulation: release 2 mediators histamine and leukotrienes

3. mediators call neutrophils to site causing inflammatory response, increase mucous production

4. breathing difficulty

increase blood vessel permiability

histamine

prolonged contraction of smooth muscles

leukotrienes

are allergic reactions localized or systemic

localized

allergic reaction

antigens are usually …

ingested or inhaled

signs and symtpoms

• eye entry: watery eyes

• nose entry: sneezing

allergic reactions

treatment

• antihistamines

allergic reactions

block histamines or blockallergen from binding to IGE

antihistamines

anaphylactic shock

• localized or systemic?

systemic

anaphylactic shock

antigens are usually …

ingested injected

descriptor

• may result in circulatory collapse

anaphylactic shock

anaphylactic reactions

treatment: epinephrine

anaphylactic shock

allergic reaction is an example of

anaphylactic reactions

anaphylactic shock is an example of

anaphylactic reactions

what is the method used to prevent anaphylactic reactions

desensitization program

what is the first step of anaphylactic desensitization program

skin test

what is the goal of the second stage of the anaphylactic desensitization program

immune system response with igG not igE

what does igG act as in the desensitization program of anaphylactic reactions

blocking antibody that neutralizes antigen

what are the 4 examples of cytotoxic reactions

1. blood transfusion reactions

2. hemolytic disease of newborns

3. thromocytopenic purpura

4. hemolytic anemia

antigens involved bound on fixed location on cell surface

cytotoxic reactions

antibodies involved

• IgG IgM

cytotoxic reactions

antibodies target antigens on blood cells or tissue cells

cytotoxic reactions

cell lysis is caused by compliment activation or damaged macrophages

cytotoxic reactions

involves ABO blood types and Rh groups

cytotoxic blood transfusion reactions

antigens present on RBC surface

cytotoxic blood transfusion reaction

gives rise to blood types

cytotoxic blood transfusion reactions

blood transfusion reaction is an exmaple of

cytotoxic reactions

hemolytic disease of newborns is an example of

cytotoxic reactions

drug induced cytotoxic reactions are an example of

cytotoxic reactions

thrombocytopenic purpura is an example of

cytotoxic reactions

hemolytic anemia is an example of

cytotoxic reactions

descriptors

involves Rh blood groups

hemolytic disease of newborns

summarize hemolytic disease of a newborn

rh negative mom

rh positive dad

first baby born rh psotive

mom creates anti rh antibodies against baby

second baby is born rh positive and moms anti rh antibodies start attacking baby

hemolytic disease of newborn prevenition

rhogam which are anti rh antibodies

rhogam is what type of immunity…

artificial passive

what are the two examples of drug induced cytotoxic reaction

• thrombocytopenic purpura

• hemolytic anemia

summarize what drug induced cytotoxic reactions are

target cell coated with drugs → produce antibodies → bind to drugs → compliment binds → cell destroys

target cell = platelets

thrombocytopenic purpura

drug enduced cytotoxic reaction

low platelet count = purple skin

thrombocytopenic purpura

cytotoxic reaction

causes hemhorraging because not enough platelets

thrombocytopenic purpura

hemolytic anemia

• function

destroys RBC

what are two examples of immune complex reactions

1. arthus reaction

2. serum sickness

antigens are circulating NOT fixed

immune complex reactions

antibodies involved in immune complex reactions

IgG

formation of immune complexes with excessive antigens or antibodies

immune complex reactions

immune complexes lodge in basement membrane → activates compliment → attracts neutrophiles → inflammation

immune complex reaction

produce excessive antibodies

arthus immune complex reaction

side effect of toxoid vaccines (TD vaccines)

immune complex reactions

signs and symtpoms

• pain edema hemorrhaging

arthus immune complex reactions

produces excessive antigen

serum sickness immune complex reeaction

hypersensitivity to antiserums or drugs

serum sickness

immune complex activates compliment system

serum sickness

what are the two examples of delayed cell mediated reactions

1. tuberculin skin test (Mantoux test )

2. contact dermatitis

caused by TD cells

delayed cell mediated reactions

process of delayed cell mediated reactions

1. release cytokines

2. attract macrophages

3. initiate tissue damage

tuberculin skin test is an example of

delayed cell mediated reactions

contact dermatitis is an example of

delayed cell mediated reactions

why is delayed cel mediated reaction not a part of hypersensitivity reaction type one

t cells not b cells

does not use IgE

antibody involved

• IgE

anaphylactic reactions

antibodies involved

• IgG

• igM

cytotoxic reactions

antibodies involved

-igG

immune complex reaction

caused by TD cells

delayed cell mediated immune reactions