Positive staining (normal): subset of normal peripheral B cells
Positive staining (disease): myeloid leukemias and some B cell malignancies
Negative staining: normal B cells
Aka E rosette receptor, LFA-2 (leukocyte function antigen)
Function: binds CD58 / LFA-3 on antigen-presenting cells, and induces costimulatory signals in T cells
Also regulates T and NK-mediated cytolysis, inhibits apoptosis of activated peripheral T cells, mediates T cell cytokine production, regulates T cell anergy
Positive staining (normal): thymocytes (95%), mature peripheral T cells (almost all), NK cells (80-90%), thymic B cells (50%)
Micro images: extranodal NK/T cell lymphoma, nasal type
Aka OKT3
Function: complex (5 chains) of integral membrane glycoproteins assembled as a complex; has long cylasmic tail with antigen recognition activation motif; complex is then down regulated
Also subdivided into delta, epsilon, gamma subtypes
Cylasmic expression at early T cell differentiation, then membranous expression
Most specific T cell antibody
Positive staining (normal): thymocytes, peripheral T cells, NK cells; also Purkinje cells of cerebellum
Positive staining (disease): 80% of T cell lymphomas
Negative staining: gamma delta T cell receptors, most B cell lymphomas
Micro images: CD3 epsilon-testicular NK/T cell lymphoma (figure 3D)
Micro images (AJSP subscribers): achalasia, post-transplant lymphoproliferative disease in liver
References: AJSP 2001;25:1413
Aka OKT4, T helper/inducer
On chromosome #12p
Nonpolymorphous glycoproteins belonging to immunoglobulin superfamily
Serves as HIV receptor on T cells (as do chemokine receptors CCR5 and CXCR4), macrophages, brain
CD4+ T cells are killed by HIV
Coreceptor in MHC class II-restricted antigen induced T cell activation
Binds to nonpolymorphic region of class I molecules; may increase avidity of cell-cell interactions
Positive staining (normal): thymocytes (80-90%), mature T cells (65%, T helper and CD4/CD8+ thymocytes), macrophages, Langerhans cells, dendritic cells, granulocytes
Positive staining (disease): pityriasis lichenoides
Micro images: acute demyelinating disease, extranodal NK/T cell lymphoma, nasal type
Belongs to ancient scavenger receptor family
Is physically and functionally coupled with T cell receptor-zeta-CD3 signal transducer complex
CD5+ B cells produce “generalist antibodies” - polyreactive low affinity "natural" antibodies to exogenous antigens (tetanus toxoid, lipopolysaccharide) as well as autoreactive antibodies (ssDNA, thyroglobulin, insulin)
Note: sharks only have polyreactive IgM
Note: monoreactive IgG is produced by < 0.1% of circulating B cells, from positive selection and somatic
point mutation
First line of defense against antigens; have a low activation threshold; are the only line of defense for those who cannot produce specific antibody
Produce antibodies using germ line (non mutated) configuration of gene segments, usually IgM
Production elevated in rheumatoid arthritis (27-52% of circulating B cells vs. 20% normal)
CD5 may serve as a dual receptor, giving either stimulatory or inhibitory signals depending both on the cell type and the development stage
Positive staining (normal): B cells of mantle zone of spleen and lymph nodes; B cells in peritoneal and pleural cavities; almost all T cells;
In fetus, most B cells in spleen and cord blood are CD5 positive
Positive staining (disease): B cell CLL/SLL, mantle cell lymphoma, most T malignancies, thymic carcinomas (70%)
Negative staining: spindle cell thymomas, MALT lymphoma, follicular lymphoma
Micro images: extranodal NK/T cell lymphoma, nasal type, mantle cell lymphoma (figure 3D)
Adhesion molecule mediating the binding of developing thymocytes with thymic epithelial cells
May be involved in autoimmunity and graft vs. host disease (GVHD)
Antibodies to CD6 are used to deplete T cells from bone marrow transplants to prevent GVHD
Positive staining (normal): low levels on immature thymocytes, high levels on mature thymocytes
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