CD2

CD2 is a T-cell and NK cell (80-90%) marker.  It also stains mast cells in mastocytosis disorders, and is variable in thymic B-cells (~50%).  Some cases of AML will express CD2.  CD2 does NOT stain B-cells, basophils, and mast cells in non-mastocytosis disorders.  CD2 is one of the earliest T-cell markers. 
 
Practically, CD2 is most often used as part of a T-cell panel to detect T-cell differentiation in a lymphoma of uncertain or presumed T-cell origin.  CD3 is the most commonly used T-cell marker.  Other T-cell markers include:  CD3, CD4, CD5, CD7, and CD8.  When evaluating an abnormal T-cell process it is often necessary to do a T-cell panel to look for aberrant antigen expression loss.
CD2 Expression
  • T-cells (all)
  • NK cells (80-90%)
  • Thymic B-cells (~50%)
  • Mast Cell Disorders
  • AML (Subset)
Reactivity pattern:  Membranous and cytoplasmic

Photomicrographs
CD2 - Benign Tonsil
CD2 – Benign Tonsil
CD2 - Benign Tonsil
CD2 – Benign Tonsil
CD2 - Benign Tonsil
CD2 – Benign Tonsil

References
Bone Marrow IHC.  Torlakovic, EE, et. al. American Society for Clinical Pathology Pathology Press © 2009.  pp. 16-17.
 
Seed B, Aruffo A. Molecular cloning of the CD2 antigen, the T-cell erythrocyte receptor, by a rapid immunoselection procedure. 1987.
 
Davis SJ, van der Merwe PA. The structure and ligand interactions of CD2: implications for T-cell function. Immunol Today. 1996;17: 177–187.