Type II, III, and IV Hypersensitivity Reaction

Type II hypersensitivity

Cytotoxic & Cytolytic

Common antigens in Type II

Rh factor and ABO blood group

A women with what blood type is at risk for erythroblastosis fetalis due to Rh sensitization

Rh-NEGATIVE women

When does the Rh-negative mother develop anti-Rh antibodies?

During 1st pregnancy as a response to fetal Rh antigens entering her bloodstream

When do the anti-Rh antibodies cross the placenta and damage fetal RBCs?

2nd pregnancy

What can the mother do to prevent Erythroblastosis Fetalis?

Rh sensitization is prevented by administering Rh immune globulin injections (like RhoGAM) to an Rh-negative mother during pregnancy and after events that could cause blood mixing

When is RhoGAM given?

28 weeks of pregnancy, within 72 hours of delivery if the baby is Rh-positive, and after any potential sensitizing events like miscarriage, trauma, or bleeding. 

What blood type is the universal recipient?

AB

What blood type is the universal donor?

O

What antibodies does type AB have?

None

What antigens does type AB have?

A and B

What antibodies does type O have?

A and B

What blood can type O get?

O

What antigens does type O have?

None → ANYONE CAN GET IN AN EMERGENCY

What blood can type A get?

A and O

What blood can type B get?

B and O

What blood can type AB get?

ANY!!

Type III

Immune Complex

How is type III mediated?

Antigen-antibody complexes

How is type III categorized?

Similar to type I → Systemic or local

Examples of Systemic Type III reactions

SLE

RA

Serum sickness

What immunoglobulin is involved in type three?

IgG

What happens in type III?

Immune complexes are LARGE molecules of antibody combined with antigen → due to size, hard to remove → they get LODGED IN TISSUES

What is serum sickness?

Reaction to certain medications, most commonly penicillin and other antibiotics

When does serum sickness normally develop?

within 7-12 days, sometimes as long as 3 weeks

Type IV

DELAYED-type

Examples of Type IV

Poison ivy

Translant regection

Mantoux TB test

Reaction to bacterial infection

Latex allergy

Type IV is also known as…

CELL-mediated or antibody independent

Are antibodies involved in type IV?

NO

How is type IV regulated?

T lymphocytes

When does the delayed-type reaction happen?

24-72 hours after exposure to antigen

When is a TB test read?

48-72 hours after

Reaction typical of a positive TB test

Wheal and flare reaction

• raised area with edematous fluid(wheal)

• Erythema (red flare)