Stains & CD markers

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Last staff update: 28 April 2022

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PubMed Search: CD3

Leonie Frauenfeld, M.D.
Christian M. Schürch, M.D., Ph.D.
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Cite this page: Fraunfeld L, Schürch CM. CD3. website. Accessed February 23rd, 2024.
Definition / general
  • Common antibody for identifying T cells
  • Member of immunoglobulin superfamily on 11q23
  • Also called OKT3
Essential features
  • Common antibody for identifying T cells
Clinical features
  • Cytoplasmic positivity in immature T cells (cCD3), while negative surface CD3 (sCD3)
  • Complete and membranous positivity in mature T cells (CD3)
  • Reference: Histopathology 2000;36:544
Uses by pathologists
  • Most specific T cell antibody; usually used to identify T cells in benign and malignant disorders; most antibodies are directed against epsilon chain
    • CD3 in IHC stains both membrane and cytoplasm and stains both T cells and NK cells, thus NK cell processes / lymphomas are CD3 by IHC
    • Flow cytometry can distinguish surface from cytoplasmic CD3 and therefore T cells (surface CD3+ from NK cells (surface CD3-)
    • Flow cytometry can also distinguish T cells with surface CD3 (mature T cells) from T cells with cytoplasmic CD3 but without surface CD3 (T lymphoblasts)
  • CD3 / CD20 combined immunostains are often performed in initial cytological evaluation of lymphoid rich pleural effusions but their cost effectiveness has been questioned (Diagn Cytopathol 2012;40:565)
  • Does not improve detection of gluten sensitive enteropathy when H&E sections are normal (Mod Pathol 2013;26:1241)
Microscopic (histologic) images

Contributed by Leonie Frauenfeld, M.D.

CD3+ mature T cells in lymphadenitis

CD3+ neoplastic cells in PTCL, TBX21

Positive staining - normal
  • Thymocytes, peripheral T cells (cytoplasmic expression at early T cell differentiation, then membranous expression) (Adv Biol Regul 2019;74:100638, Nat Methods 2017;14:531)
  • NK cells (CD3 epsilon, cytoplasmic in 56%, not membranous); also Purkinje cells of cerebellum
  • Note: nonspecific cytoplasmic staining may be present in plasma cells and macrophages (faint reactivity)
Positive staining - disease
Negative staining
Flow cytometry description
Flow cytometry images

Case #36

Soft tissue: anaplastic large cell lymphoma

Sample pathology report
  • Lymph node, excision:
    • Peripheral T cell lymphoma, TBX21 (see comment)
    • Comment: Lymph node with polymorphous infiltrate with atypical lymphocytic cells. The tumor cells are positive for CD3 with coexpression of CD4, CD2, CD5 and loss of CD7. CD8 marks reactive cytotoxic T cells. TFH markers (PD-1, ICOS, BCL6, CD10, CXCR13) remain negative. The tumor cells coexpress TBX21 / T bet and CXCR3 but remain negative in GATA3 and CCR4 (Blood 2019;134:2159).
Board review style question #1

The image shows the typical membranous staining pattern for CD3 in mature T cells. Which of the following is the typical staining pattern of immature T cells in CD3 immunohistochemistry?

  1. Cytoplasmic
  2. Cytoplasmic and membranous
  3. Membranous
  4. Nuclear
Board review style answer #1
A. Cytoplasmic

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