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Anticuerpos Monoclonales/química , Anticuerpos Monoclonales/inmunología , Anticuerpos Antineoplásicos/química , Anticuerpos Antineoplásicos/inmunología , Alemtuzumab , Anticuerpos Monoclonales Humanizados , Estabilidad de Medicamentos , Almacenaje de Medicamentos , Filtración , Humanos , Temperatura , Factores de TiempoRESUMEN
BACKGROUND: Flow cytometric analysis of human P2X(7) pore activity segregates variant from common P2RX7 genotypes and may serve as a biomarker for cancer, pain, inflammation, and immune responses to infection. Standardization is needed to accommodate variable sample age and instrumentation differences in a multicenter clinical trial. METHODS: CD14-PE-stained whole blood samples were treated with YO-PRO-1 combined with a P2X(7) agonist (BzATP) or control, followed by the addition of PI after closure of the P2X(7) pore. Recalled instrument settings from previous publications were used to adapt a standardized fluorescent particle-adjusted set-up method. Experiments were performed to compare the two methods while evaluating components of systematic variability and facilitating reliable processing of samples with varied ages. RESULTS: The median YO-PRO-1 fluorescence of BzATP-treated samples had less variability when collected by the bead-adjusted method and was less influenced by the compensation strategy used. The average day-to-day coefficient of variance for assessments of P2X(7) pore activity by this method was 0.11 +/- 0.04, and the exclusion of nonviable cells was found to accommodate samples aged up to 4 days after phlebotomy. The bead-adjusted set-up method produced measurements differing by only 2.0% +/- 1.5% on two analog cytometers, and within similar decades when comparing analog to digital instruments. CONCLUSIONS: These results provide a standardized method for quantitative flow cytometric analysis of P2X(7) receptor phenotypes in blood monocytes with minimal intralaboratory variation and potential for interlaboratory comparisons that can greatly facilitate multicenter functional genomic clinical studies.
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Ensayos Clínicos como Asunto , Citometría de Flujo/métodos , Estudios Multicéntricos como Asunto , Receptores Purinérgicos P2/metabolismo , Adenosina Trifosfato/análogos & derivados , Envejecimiento/efectos de los fármacos , Asma/diagnóstico , Benzoxazoles , Supervivencia Celular/efectos de los fármacos , Citometría de Flujo/instrumentación , Fluorescencia , Humanos , Receptores de Lipopolisacáridos/metabolismo , Monocitos/citología , Monocitos/efectos de los fármacos , Flebotomía , Compuestos de Quinolinio , Receptores Purinérgicos P2X7RESUMEN
The role of SNAP-25 (synaptosomal associated protein of 25 kDa) isotypes in the neurotransmitter release process was examined by varying their relative abundance during PC12 cell differentiation induced by nerve growth factor (NGF). Norepinephrine release by NGF-differentiated PC12 cells is more sensitive to type A botulinum toxin (BoNT/A) than by nondifferentiated cells, while both differentiated and nondifferentiated PC12 cells are equally sensitive to type E botulinum toxin (BoNT/E). The differential sensitivity to BoNT/A corresponds to an altered susceptibility of SNAP-25 isotypes to BoNT/A cleavage in vitro, whereas both isotypes are equally vulnerable to cleavage by BoNT/E. Using recombinant SNAP-25 preparations, we show that BoNT/A cleaves SNAP-25b (present in differentiated cells) 2-fold more readily than SNAP-25a (present in both differentiated and nondifferentiated cells). Structural studies using far-ultraviolet circular dichroism (UV--CD) and thermal denaturation suggest a difference in the polypeptide folding as the underlying molecular basis for the differential sensitivity of SNAP-25b and SNAP-25a to BoNT/A cleavage. We propose differential roles for SNAP-25b and SNAP-25a in the neurotransmitter release process since our results suggest that BoNT/A inhibits neurotransmitter release by primarily cleaving SNAP-25b.