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Failure in IgA secretion by surface IgA-positive B cells in common variable immunodeficiency (CVID)
L J Scott1, A Bryant, A D Webster
1Immunodeficiency Diseases Research Group, Clinical Research Centre, Harrow, UK.
Clinical and Experimental Immunology
|January 1, 1994
Summary
Patients with Common Variable Immunodeficiency (CVID) show a profound defect in secreting IgA. Despite this, IgA-expressing B cells are present, suggesting a secretion issue rather than a switching problem.
Area of Science:
- Immunology
- Clinical Medicine
Background:
- Common Variable Immunodeficiency (CVID) is an acquired disorder characterized by low serum immunoglobulins.
- Current classification of CVID patients is based on B cell secretion of IgM and IgG in response to IL-2.
Purpose of the Study:
- To extend CVID patient classification by assessing IgA secretion and the presence of circulating IgA+ B cells.
- To investigate the nature of the immunoglobulin secretion defect in CVID.
Main Methods:
- In vitro assessment of IgA secretion by B cells from CVID patients and healthy donors.
- Flow cytometry analysis to quantify IgA+ B cells in the circulation of CVID patients.
Main Results:
- Nearly all CVID patients' B cells failed to secrete IgA in vitro, unlike normal donors who showed spontaneous IgA secretion.
- The defect in IgA secretion in CVID is more severe than for IgM or IgG.
- CVID patients exhibited normal percentages of IgA+ B cells in circulation, despite the secretion defect.
Conclusions:
- CVID is associated with a significant impairment in IgA secretion.
- The presence of normal IgA+ B cell numbers suggests a defect in immunoglobulin secretion rather than isotype switching in CVID.