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Updated: Aug 15, 2026
A Combinatorial Single-cell Approach to Characterize the Molecular and Immunophenotypic Heterogeneity of Human Stem and Progenitor Populations
Published on: October 25, 2018
Heterogeneity of CD44 expression among human B-cell subpopulations
G Kremmidiotis1, J Ridings, M Hicks
1Department of Molecular Genetics, Adelaide Women's and Children's Hospital and Flinders University, South Australia.
Insights
Germinal center B cells express unique forms of CD44, differing from other B cells. This finding highlights the diverse CD44 protein variants based on B-cell differentiation state.
Area of Science:
- Immunology
- Molecular Biology
- Cell Biology
Background:
- CD44 is a cell surface glycoprotein involved in cellular adhesion and signal transduction.
- B-cell differentiation involves changes in CD44 expression levels.
Purpose of the Study:
- To investigate the different forms of CD44 expressed by B cells.
- To determine if CD44 expression varies with B-cell differentiation state.
Main Methods:
- Immunofluorescence using CD44 antibodies (including A1G3).
- Western blotting and immunoprecipitation of lymphocyte fractions.
- RT-PCR and Southern blotting of sorted B-cell subpopulations.
Main Results:
- Germinal center B cells show distinct CD44 reactivity compared to other B cells, identified by antibody A1G3.
- Differential expression of CD44 bands observed between germinal center and non-germinal center B cells.
- B cells express multiple CD44 splice isoforms and variants, dependent on differentiation stage.
Conclusions:
- B cells express diverse CD44 forms, including splice variants and A1G3-distinguished variants.
- The specific CD44 form expressed is contingent upon the B-cell differentiation state.
Abstract:
CD44 is a widely distributed cell surface glycoprotein that participates in a number of cellular adhesion and signal transduction processes. Germinal center B cells express very low levels of CD44, whereas their precursors and differentiation products express much higher levels. In immunofluorescence studies comparing 20 antibodies classified as being against the hematopoietic isoform of CD44, one antibody, A1G3, was unreactive with germinal center B cells, whereas the other antibodies showed low intensity but definite reactivity. Western blotting and sequential immunoprecipitation studies of lysates from density-separated lymphocyte fractions showed two bands that were differentially expressed and reacted differently with A1G3 compared with the other CD44 antibodies. These results suggest that germinal center B cells and non-germinal center B cells express different forms of CD44. Of 21 malignant B-cell populations examined, 5 showed reactivity with a "standard" CD44 reagent and significantly reduced reactivity with A1G3, while one sample showed the opposite pattern and the remainder were positive for both reagents. Of 10 cell lines studied, 5 were differentially stained by A1G3 and a standard CD44 antibody. PCR amplification of reverse transcribed mRNA from sorted human tonsil B-cell subpopulations and Southern blotting showed that B cells express a number of splice isoforms of CD44. These results demonstrate that B cells express multiple forms of CD44; both splice insert isoforms and variants distinguished by A1G3; the form of CD44 expressed depends on B-cell differentiation state.
