Hypersensitivity medical comic

This comic works through the four Gell and Coombs types of hypersensitivity, the times the immune system overreacts and harms the body. It follows IgE-coated mast cells from sensitisation to anaphylaxis, antibody attacks on cells, immune complexes lodging in tissues and slow T-cell-driven reactions, with clinical examples of each.

For MBBS, NEET-PG, FMGE, NEXT and USMLE revision.

Hypersensitivity: what the comic covers

High-yield points

Hypersensitivity is an exaggerated or inappropriate immune response that damages the host; Gell and Coombs grouped it into four types.
Type I (immediate) is IgE-mediated: after sensitisation, IgE coats mast cells and basophils, and re-exposure triggers histamine release within minutes.
Type I ranges from local atopy (hay fever, asthma, eczema) to systemic anaphylaxis, with immediate and late phases.
Systemic anaphylaxis is an emergency treated first with intramuscular adrenaline; the Prausnitz–Küstner reaction showed that the allergic factor (IgE) could be transferred in serum.
Type II (cytotoxic) involves IgG or IgM against cell-surface antigens, acting through complement-dependent cytotoxicity, ADCC or antibody-dependent cell dysfunction — e.g. transfusion reactions, haemolytic disease of the newborn, Goodpasture's syndrome, Graves' disease and myasthenia gravis.
Type III involves antigen–antibody complexes depositing in vessels and tissues and activating complement — e.g. serum sickness, Arthus reaction, SLE, post-streptococcal glomerulonephritis.
Type IV (delayed) is mediated by T cells and macrophages, peaking at 48–72 hours — e.g. tuberculin test, contact dermatitis, granulomas.
Types I–III are antibody-mediated; type IV is the only cell-mediated type.

Quick questions

What are the four types of hypersensitivity?

Type I is immediate and IgE-mediated; type II is cytotoxic, with antibodies against cell surfaces; type III is immune-complex-mediated; type IV is delayed and T-cell-mediated.

Which hypersensitivity type is the tuberculin (Mantoux) test?

Type IV, delayed-type hypersensitivity. Sensitised T cells and macrophages cause induration that peaks at 48–72 hours.

Is anaphylaxis type I hypersensitivity?

Yes. Allergen cross-links IgE on mast cells and basophils, releasing histamine and other mediators throughout the body within minutes.

Is this comic free to read?

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From the blog

Type 1 hypersensitivity

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