Quick Review Cards for Medical Laboratory Science

Hypersensitivity Reactions Immunology Review 387

TYPE I: TYPE II: TYPE III: IMMUNE TYPE IV: T-CELL

ANAPHYLACTIC CYTOTOXIC COMPLEX DEPENDENT

Key reactant(s)

Mechanism

Onset of
symptoms

Examples

T cells

Release of cytokines

Delayed (sensitization after

1st contact with ag, symp-

toms upon reexposure).

Contact dermatitis, hypersen-

sitivity pneumonitis, tuber-

culin skin test

IgG, IgM, complement,

soluble antigens

Deposits of ag-ab com-

plexes in tissues

Immediate

Arthus rxn, serum sick-

ness, systemic lupus

erythematosus (SLE),

rheumatoid arthritis (RA)

IgE

Release of mediators

from mast cells &

basophils

Immediate

Anaphylaxis, hay

fever, asthma, food

allergies

IgG, IgM, complement,

cellular antigens

Cytolysis due to ab &

complement

Immediate

Transfusion reactions,

hemolytic disease of

newborn, autoimmune

hemolytic anemia