CD21 (CR2, C3d receptor and EBV receptor) is expressed strongly on mature B-cells, follicular dendritic cells (FDC) and weakly on immature thymocytes and T-lymphocytes. In B-cell ontogeny, CD21 appears after the pre-B-stage, is maintained during peripheral B-cell development and is lost upon terminal differentiation into plasma cells. Immunohistological analysis of FDC in paraffin sections of Non-Hodgkin lymphoma (NHL) with this antibody demonstrates a nodular and usually dense and sharply defined FDC meshwork in follicular lymphomas and a loose, ill-defined FDC of varying size in some diffuse lymphoma types. Precursor B-cell lymphoma (lymphoblastic lymphomas), Burkitt lymphomas, plasmacytomas and hairy cell leukemias consistently lack CD21 expression. CD21 is expressed on follicular dendritic cell sarcoma.
CD23 is expressed on a subpopulation of peripheral blood cells, B-lymphocytes and on EBV transformed B-lymphoblastoid cell lines. It is used to differentiate B-cell chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) from other entities and can remain present in CLL/SLL that has undergone large cell transformation.
In AML, erythroblasts may exhibit GPHA (CD235a). It may be a weak or negative stain as it tends to stain more erythroid precursors and red blood cells.
The interleukin-2 receptor is designated CD25. It is expressed on hairy cell leukemia and adult T-cell leukemia/lymphoma, classical Hodgkin lymphoma, and a subset of other peripheral T-cell lymphomas.
The CD3 antigen has a cytoplasmic expression at early T-cell differentiation, then membranous expression; CD3 is the most specific T-cell antibody. In diseased cells, CD3 stains most T-cell lymphomas. Only rare B cell lymphomas may be positive for CD3.
CD30 is a lymphocyte activation antigen, related to tumor necrosis factor. It is expressed in activated B-, T- and NK cells. Positive staining is seen in infectious mononucleosis, lymphocytes infected with HIV, HTLV-1, EBV, HHV8 or hepatitis B, Reed-Sternberg cells, anaplastic large cell lymphomas (90%), lymphomatoid papulosis, peripheral T-cell lymphomas, and embryonal cell tumors.
CD31 is a 130kDa transmembrane glycoprotein that is shared by vascular lining cells, megakaryocytes and platelets. This marker has excellent sensitivity and is highly restricted to endothelial neoplasms among all tumors of soft tissue. 100% of angiosarcomas and hemangiomas are CD31 positive. However, Kaposi’s Sarcoma (KS) is labeled more consistently by CD34 than by CD31. CD31 has also been used as a prognostic marker measuring tumor angiogenesis.
CD33 can identify cells of myeloid and monocytic lineage, leukemias and myeloproliferative neoplasms derived from these cells.
CD34, a single chain transmembrane glycoprotein, is selectively expressed on human lymphoid and myeloid hematopoietic progenitor cells and endothelial cells. The CD34 antibody labels many gastrointestinal stromal tumors (GIST), dermatofibrosarcoma protuberans, solitary fibrous tumor and a subset of sarcomas.
CD38 is a transmembrane protein that is highly expressed on thymocytes. It is also present on activated T-cells and terminally differentiated B-cells (plasma cells). Other reactive cells include NK cells, monocytes, macrophages and dendritic cells. CD38 may be detected on cells from multiple myeloma, acute lymphoblastic leukemia (ALL, B and T) and some acute myeloid leukemia (AML).