Hygiene Atlas

Atlas · Plate VI · Microbiology and Immunology · 07

Antibodies and hypersensitivity

There are five antibody classes. IgG is the most plentiful and the only one that crosses the placenta, secretory IgA guards saliva and mucosa, IgM is made first, and IgE drives immediate allergy. Hypersensitivity has four types: I (IgE: anaphylaxis, latex allergy), II (cytotoxic: pemphigus vulgaris), III (immune complex: lupus) and IV (delayed, T cell: contact dermatitis, lichenoid reactions).

High-yield facts · 9

  1. Five antibody classes: IgG, IgA, IgM, IgE, IgD.S50
  2. IgG is the most abundant in serum and the only one that crosses the placenta.S50
  3. Secretory IgA protects mucosal surfaces and is the main antibody in saliva and breast milk.S50
  4. IgM is a pentamer and is the first antibody made in a new infection.S50
  5. Type I (immediate, IgE): anaphylaxis, asthma, hay fever, latex allergy.S50
  6. Type II (cytotoxic, antibody against cells): transfusion reactions, pemphigus vulgaris.S50
  7. Type III (immune complex): serum sickness, lupus.S50
  8. Type IV (delayed, T cell, 24-72 hours): contact dermatitis, TB skin test, lichenoid reactions.S50
  9. Pemphigus vulgaris targets desmosomes (intraepithelial blister, positive Nikolsky sign); mucous membrane pemphigoid targets hemidesmosomes (subepithelial blister).T5

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