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Difference in CD22 molecules in human B cells and basophils
Ken Toba1, Haruo Hanawa, Ichiro Fuse
1First Department of Internal Medicine, Niigata University Hospital, Niigata City, Japan. tobaken@med.niigata-u.ac.jp
Experimental Hematology
|March 8, 2002
Summary
Human basophils express CD22 molecules, differing in antigenicity from B cells. Structural differences in CD22 conformation, specifically disulfide bonds, likely explain this variation in antigen recognition.
Area of Science:
- Immunology
- Molecular Biology
Background:
- CD22 is typically found on B cells.
- Human basophils also express CD22 molecules.
- Antibody binding to CD22 differs between B cells and basophils.
Purpose of the Study:
- Investigate the structural basis for differential CD22 antigenicity in human B cells versus basophils.
- Clarify the role of CD22 molecular structure in antigen recognition.
Main Methods:
- Isolated human B cells and basophils using MACS.
- Performed RT-PCR and sequencing of CD22 mRNA (exons 3-8).
- Conducted Western blotting analysis of CD22.
Main Results:
- CD22 mRNA sequences in basophils and B cells were identical in analyzed exons.
- Reduced CD22 peptides from basophils reacted with antibodies recognizing different epitopes.
- CD22 molecular size was consistent (130 kDa) in both cell types.
Conclusions:
- Disulfide bonds and 3D conformation of CD22 likely dictate antigenicity differences.
- Structural variations in the CD22 ligand-binding domain suggest conformational specialization.
- These findings may relate to CD22's interaction with different ligand isoforms.