CD20; B-lymphocyte antigen CD20; membrane-spanning 4-domains subfamily A member 1; B-lymphocyte surface antigen B1; Leu-16; Bp35 (MS4A1)

Function

• CD20 regulates an early step in the initiation of the cell cycle
• may be involved in the regulation of B-cell activation & proliferation
• may regulate a Ca+2 channel
• not shed from the cell surface & does not internalize upon antibody binding
• phosphorylated
• might be functionally regulated by protein kinase(s)

Structure

belongs to the MS4A family

Compartment

membrane

Expression

• appears on pre B cells after CD19; otherwise similar to CD19 in expression
• CD20 is present on pre B & mature B cells but not plasma cells
• most B cells (after CD10 & CD19 expression, before CD21/CD22)
• mature B cells until plasma cell stage
• follicular dendritic cells
• small amounts expressed in benign & neoplastic T cells
• non-hematopoietic cells, plasma cells & most T cells stain negatively with antibody

Pathology

• expressed in:
  • B cell lymphoma ~90%
  • pre-B ALL/LBL ~40%
  • lymphocyte predominant Hodgkin's lymphoma ~80%
  • spindle cell thymomas

Pharmacology

• rituximab (Rituxan) is a monoclonal antibody which specifically binds CD20
• it is used in treatment of patients with relapsed or refractory, low-grade or follicular, CD20-positive, B-cell non-Hodgkin's lymphoma
• britumomab (Zevalin) & bositumomab (Bexxar) are also monoclonal antibodies against CD20

More general terms

• CD antigen
• phosphoprotein
• transmembrane 3 protein

Additional terms

• CD19; B-lymphocyte antigen CD19; differentiation antigen CD19; B-lymphocyte surface antigen B4; Leu-12
• rituximab (Rituxan, Mabthera, Truxima, Ruxience, Riabni)

Database

• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:931
• OMIM: https://mirror.omim.org/entry/112210
• UniProt: http://www.uniprot.org/uniprot/P11836.html