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Differentiation between neutrophil-bound antibodies and immune complexes
R J Klaassen1, R Goldschmeding, A B Vlekke
1Central Laboratory of the Netherlands Red Cross Blood Transfusion Service, Amsterdam.
British Journal of Haematology
|March 1, 1991
Summary
Distinguishing neutrophil-bound immune complexes (IC) from anti-neutrophil antibodies is crucial. A novel eluate reactivity test effectively differentiates these, overcoming limitations of the C1q-binding test for characterizing neutrophil-bound immunoglobulins.
Area of Science:
- Immunology
- Clinical Chemistry
Background:
- Neutrophil-bound immunoglobulins (NBIg) in chronic diseases can be immune complexes (IC) or anti-neutrophil antibodies.
- The C1q-binding test is currently used to identify NBIg, but has limitations.
Purpose of the Study:
- To develop and validate a method for accurately characterizing NBIg.
- To differentiate between IC and anti-neutrophil antibodies bound to neutrophils.
Main Methods:
- Utilized bivalent IC and heat-aggregated IgG as IC models, and neutrophil alloantibodies as antibody models.
- Assessed NBIg binding to neutrophils and elution properties.
- Employed a C1q-binding test and developed an eluate reactivity assay.
Main Results:
- Heat-aggregated IgG was detected by the C1q-binding test, but bivalent IC were not.
- Bivalent IC failed to bind C1q, explaining their absence in the C1q-binding test.
- Eluates from neutrophils sensitized with antibodies reacted with donor neutrophils, while eluates from neutrophils with bound IC did not.
Conclusions:
- A negative C1q-binding test does not exclude the presence of neutrophil-binding IC.
- Eluate reactivity is a reliable method to distinguish between anti-neutrophil antibodies and bound IC on neutrophils.