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Microtubules in PMNs from patients with familial Mediterranean fever
Abstract:
Polymorphonuclear (PMN) cells derived from patients with Familial Mediterranean Fever (FMF) were evaluated in vitro for the function and concentration of their microtubules. Using the time-decay colchicine binding assay to determine the tubulin concentration in PMN cells, no difference was found in PMN cells derived from FMF patients in comparison with those from normal healthy subjects. Colchicine treatment had no effect on the detectable tubulin concentration in the cells. The mobility of fluorescent con A(F-con A)-receptor complexes on PMN membranes was used to test the function of the microtubules. PMNs from untreated FMF patients showed the same pattern of con A cap formation as seen in normal cells. PMNs derived from colchicine treated patients, however, showed 22-32% spontaneous cap formation. These cells also showed 10-30% more capping in comparison with normal or untreated FMF cells, for any given in vitro colchicine concentration, suggesting that at therapeutic doses, the colchicine does accumulate in the PMNs in vivo. We were unable to demonstrate a microtubule defect in the neutrophils from FMF patients in these studies.
Insights
This study found no microtubule defects in neutrophils from Familial Mediterranean Fever (FMF) patients. Colchicine treatment in FMF patients did show increased cell capping, suggesting in vivo drug accumulation.
Area of Science:
- Immunology
- Cell Biology
- Rheumatology
Background:
- Familial Mediterranean Fever (FMF) is an autoinflammatory disease.
- Neutrophils (PMN) play a role in FMF pathogenesis.
- Microtubule function in FMF neutrophils is not well understood.
Purpose of the Study:
- To investigate microtubule concentration and function in neutrophils from FMF patients.
- To assess the in vitro effects of colchicine on FMF neutrophils.
- To determine if FMF is associated with an intrinsic neutrophil microtubule defect.
Main Methods:
- Tubulin concentration was measured using a time-decay colchicine binding assay.
- Microtubule function was assessed by examining con A receptor-membrane mobility (con A cap formation).
- Neutrophils from healthy subjects, untreated FMF patients, and colchicine-treated FMF patients were analyzed.
Main Results:
- No significant difference in tubulin concentration was observed between FMF and healthy neutrophils.
- Neutrophils from untreated FMF patients exhibited normal con A cap formation.
- Neutrophils from colchicine-treated FMF patients showed increased spontaneous cap formation and enhanced capping response to in vitro colchicine.
Conclusions:
- The study did not identify an intrinsic microtubule defect in neutrophils from FMF patients.
- Colchicine appears to accumulate in neutrophils in vivo at therapeutic doses.
- The findings suggest that FMF pathogenesis may not directly involve neutrophil microtubule dysfunction.