[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Immunology](https://durgical.com/en/immunology/) › [Hypersensitivity](https://durgical.com/en/immunology/#a-hypersensitivity) › Type II hypersensitivity (antibody against cells)

[Immunology](https://durgical.com/en/immunology/) · [Hypersensitivity](https://durgical.com/en/immunology/#a-hypersensitivity)

# Type II hypersensitivity (antibody against cells)

- Process

Antibodies stick to the body's own cells or tissue. They mark them for destruction, or they switch a receptor on or off without killing the cell.

Updated 2026-11-01

**See it in 3D:** [Thyroid gland](https://durgical.com/en/anatomy/thyroid-gland/) · [Spleen](https://durgical.com/en/anatomy/spleen/)

## Key points

- IgG or IgM against a fixed antigen on a cell or matrix.
- Four ways to harm: complement, opsonization, ADCC and receptor stimulation or blockade.
- Graves (stimulates TSH receptor) and myasthenia gravis (blocks acetylcholine receptor) are type II without cell death.
- Hemolytic transfusion reaction and hemolytic disease of the newborn are type II; the direct Coombs test is positive.
- Rheumatic fever is type II through cross-reaction between streptococcal M protein and heart proteins.

## What it is

In type II hypersensitivity, IgG or IgM binds an antigen that is fixed on a cell surface or in the extracellular matrix. The bound antibody can trigger complement, flag the cell for phagocytes in the spleen and liver, recruit NK cells (ADCC), or act on a receptor directly. It explains blood-group reactions, many autoimmune cytopenias and two classic receptor diseases, Graves disease and myasthenia gravis.

## Key facts

- Antigen is fixed on a cell or matrix; in type III it is soluble and travels in complexes.
- Pernicious anemia is also type II: antibodies against intrinsic factor and gastric parietal cells.
- Drugs can bind red cells or platelets and turn them into targets (drug-induced hemolytic anemia or thrombocytopenia).

## Type II mechanisms with examples

| Mechanism | What happens | Disease | Target antigen |
| --- | --- | --- | --- |
| Complement lysis and opsonization | Membrane attack complex bursts the cell, or C3b and IgG mark it for macrophages | Acute hemolytic transfusion reaction, autoimmune hemolytic anemia, hemolytic disease of the newborn | ABO and Rh antigens on red cells |
| Antibody-dependent cellular cytotoxicity (ADCC) | NK cells and macrophages bind the antibody's Fc and kill the coated cell | Immune thrombocytopenia | Platelet glycoproteins |
| Complement-driven inflammation | C5a recruits neutrophils that damage the tissue | Anti-GBM disease (Goodpasture), acute rheumatic fever | Type IV collagen; streptococcal M protein cross-reacting with cardiac myosin |
| Receptor stimulation | Antibody turns the receptor on without the hormone | Graves disease | TSH receptor |
| Receptor blockade | Antibody blocks and removes the receptor | Myasthenia gravis | Acetylcholine receptor at the neuromuscular junction |
| Loss of adhesion | Antibody separates cells from each other | Pemphigus vulgaris | Desmogleins |

## In the lab

- Direct Coombs (direct antiglobulin) test: detects IgG or complement already on the patient's red cells.
- Indirect Coombs test: detects free antibodies in serum, used in crossmatch and prenatal screening.

## Memory aid

In type II the antibody signs its name on the cell itself: on a red cell it is a death sentence, on a receptor it is a switch.

## Test yourself

Think of the answer, then tap the question to see it.

## What is the target of the stimulating antibody in Graves disease?

The TSH receptor on thyroid cells. The antibody mimics TSH, so the gland grows and makes too much hormone.

## Which test shows that a patient's own red cells are coated with antibody or complement?

The direct Coombs (direct antiglobulin) test. It is positive in autoimmune hemolysis, hemolytic transfusion reactions and hemolytic disease of the newborn.

## How does antibody-dependent cellular cytotoxicity kill a cell?

NK cells or macrophages grab the Fc tail of IgG bound to the cell and release perforin and granzymes, killing it without complement.

## In myasthenia gravis, why is muscle weakness worse with repeated use?

Antibodies block and reduce acetylcholine receptors, so with repeated firing too few receptors respond and contraction fades.

[Add to my cards (4)](https://durgical.app/estudiar/?add=/en/immunology/type-ii-hypersensitivity/)

## See it in 3D

The structures of Durgical's 3D anatomy where it is found.

- [Thyroid gland](https://durgical.com/en/anatomy/thyroid-gland/)
- [Spleen](https://durgical.com/en/anatomy/spleen/)

## Related

- [Hypersensitivity: the four types compared](https://durgical.com/en/immunology/hypersensitivity-the-four-types-compared/)
- [Complement: three pathways, MAC, regulators](https://durgical.com/en/immunology/complement-three-pathways-mac-regulators/)
- [Transfusion reactions](https://durgical.com/en/immunology/transfusion-reactions/)
- [ABO and Rh blood groups, hemolytic disease of the newborn](https://durgical.com/en/immunology/abo-and-rh-blood-groups-hemolytic-disease-of-the-newborn/)
- [Direct and indirect Coombs test](https://durgical.com/en/immunology/direct-and-indirect-coombs-test/)
- [Autoantibodies: the table to know](https://durgical.com/en/immunology/autoantibodies-the-table-to-know/)
- [Molecular mimicry and post-infectious autoimmunity](https://durgical.com/en/immunology/molecular-mimicry-and-post-infectious-autoimmunity/)

## Related conditions

- [Graves disease (hyperthyroidism)](https://durgical.com/en/conditions/graves-disease/)
- [Rheumatic heart disease](https://durgical.com/en/conditions/rheumatic-heart-disease/)
- [Pernicious anaemia](https://durgical.com/en/conditions/pernicious-anaemia/)
- [Neonatal jaundice](https://durgical.com/en/conditions/neonatal-jaundice/)

## Microorganisms

- [Streptococcus pyogenes](https://durgical.com/en/microbiology/streptococcus-pyogenes/)

[← All of immunology](https://durgical.com/en/immunology/)

Educational content on the immune system; not a treatment or individual vaccination guide and no substitute for a health professional's advice. No doses are given.

Sources: [Type II Hypersensitivity Reaction](https://www.ncbi.nlm.nih.gov/books/NBK563264/) (StatPearls Publishing (NCBI Bookshelf), 2025); [Autoimmune responses are directed against self antigens](https://www.ncbi.nlm.nih.gov/books/NBK27155/) (Garland Science (Janeway's Immunobiology, 5th ed., NCBI Bookshelf), 2001); [ABO Blood Group System](https://www.ncbi.nlm.nih.gov/books/NBK580518/) (StatPearls Publishing (NCBI Bookshelf), 2025).

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Source: https://durgical.com/en/immunology/type-ii-hypersensitivity/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/immunology/type-ii-hypersensitivity/