CD77: an antigen of germinal center B cells entering apoptosis.

Abstract

We have previously reported that a neutral glycolipid (globotriosylceramide; Gb3) was specifically expressed on Burkitt's lymphoma cells and on a subset of germinal center tonsillar B lymphocytes. Recently the Gb3 molecule was recognized as a new B cell differentiation antigen and now defines the CD77 cluster. Here we report an extensive phenotypic and functional characterization of the tonsillar CD77+ B lymphocytes. These cells have a low buoyant density and are thus purified using a Percoll gradient. They express various B cell antigens such as CD19, CD20, CD21, CD22 and CD40, as well as the adhesion molecules LFA-1, LFA-3 and CD44. They are positive for surface IgM and negative for surface IgD. Although these results suggest a phenotype of activated B cells, the CD77+ cells are negative for the classical activation antigens: CD23 (the low-affinity Fc receptor for IgE), CD25 [the interleukin (IL) 2 receptor alpha chain] and CD71 (the transferrin receptor). Proliferation and protein synthesis of CD77+ cells was measured after stimulation with a range of mitogens and IL. None of the agents tested are able to induce proliferation and protein synthesis with the exception of a combination of recombinant IL 4 plus anti-CD40 antibody. When examined by electron microscopy, CD77+ B lymphocytes present a morphology similar to that of cells undergoing programmed cell death, also called apoptosis (i.e. chromatin condensation, nuclear fragmentation, membrane blebbing). As shown by direct examination of DNA, these CD77+ cells are indeed in the process of apoptosis. Treatment of the CD77+ cells by recombinant IL 4 and anti-CD40 antibody prevents apoptosis. All these results suggest that the CD77 molecule defines a B lymphocyte maturation pathway, specific for germinal center, where the cells undergo programmed cell death.

• Authors: M Mangeney, Y Richard, D Coulaud, T Tursz, J Wiels
• Journal: European journal of immunology (Eur J Immunol) Vol. 21 Issue 5 Pg. 1131-40 (May 1991) ISSN: 0014-2980 [Print] Germany
• PMID: 1709864 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Antibodies, Monoclonal
• Antigens, CD
• Antigens, Differentiation, B-Lymphocyte
• CD40 Antigens
• Glycolipids
• Receptors, Lymphocyte Homing
• Trihexosylceramides
• globotriaosylceramide
• DNA

Topics

• Antibodies, Monoclonal (immunology)
• Antigens, CD (physiology)
• Antigens, Differentiation, B-Lymphocyte (physiology)
• B-Lymphocytes (immunology, physiology, ultrastructure)
• CD40 Antigens
• Cell Separation
• Cell Survival
• DNA (metabolism)
• Glycolipids (analysis)
• Humans
• Lymphocyte Activation
• Phenotype
• Protein Biosynthesis
• Receptors, Lymphocyte Homing (physiology)
• Trihexosylceramides (analysis, physiology)