Or is there any specific cell surface marker that I can look for that suggests its activated?
While Dmitry's answer is at molecular level, a simple test I suggest would be centrifuging an aliqot of the neutrophils at low speed (700xg) for 5-10 minutes and try to resuspend the pellet in serum free RPMI (serum cytokines can activate neutrophils if it has interferons, if the pellet tends to aggregate and not becoming single cells, that means the neutrophils are activated (activated neutrophils clumps very strongly). This is the reason why neutrophils are spun at low speeds with the BRAKES OFF (to reduce vibration induced activation). Also do not use 1ml pipette tips as such to resuspend the pellet because neutrophils can get activated when the pellet rush into the narrow tips. Either cut the end of the tip to make the opening larger or use 5ml or 10 ml serological pipettes to resuspend the pellet. Good luck..!!
Obviously, to see activation of neutrophils, respiratory burst and degranulation are estimated. I think, vast majority of surface molecules of neutrophils are common with another celIs of myeloid lineage (so, they are not specific for neutrophils). To see activation, it would be most interesting (for me) to search for increase in CD83, CD54, CD80 and HLA-DR molecules on PBMC with high SSC. Also, there are evidences indicating decrease in CD31 on the surface of neutrophils (this may indicate that neutrophil already migrated via tissues). After immunization of mice with allogeneic tumors, we observed interesting population of neutrophils Gr-1+CD31-CD80+C2int, expressing IL-12 in mouse spleen. It is noteworthy, that live neutrophils after activation can acquire some properties of dendritic cells and can polarize to inflammatory type 1 immune response. May be, this type of neutrophils is alternative to MDSC. Hope, another researchers will be able to answer your question more specifically or will maintain discussion.
While Dmitry's answer is at molecular level, a simple test I suggest would be centrifuging an aliqot of the neutrophils at low speed (700xg) for 5-10 minutes and try to resuspend the pellet in serum free RPMI (serum cytokines can activate neutrophils if it has interferons, if the pellet tends to aggregate and not becoming single cells, that means the neutrophils are activated (activated neutrophils clumps very strongly). This is the reason why neutrophils are spun at low speeds with the BRAKES OFF (to reduce vibration induced activation). Also do not use 1ml pipette tips as such to resuspend the pellet because neutrophils can get activated when the pellet rush into the narrow tips. Either cut the end of the tip to make the opening larger or use 5ml or 10 ml serological pipettes to resuspend the pellet. Good luck..!!
Often the isolation procedures turn neutrophils to inflammatory cells. The RB reaction kinetics for serum opsonized zymosan particles will change - normally it becomes faster when cells are activated. Use calcium free buffers with EDTA and low temperatures to avoid priming.
Can you measure receptor expression with flow cytometer?
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