Hey
Perhaps one of you can help me.
After adding healthy human serum 10% to a well of neutrophils, they change morphologically and appear dead. Why does this happen?
Hi Jim,
Of course, serum is just the fluid remaining after blood or plasma has clotted, so consider what is present in serum. This includes large amounts of fibronectin and lots of immunoglobulins (which bind to Fc receptors), remnants of the complement cascade like C5a and C3b, lots of PDGF and other platelet derived factors, and probably some hemoglobin from lysed RBCs P. The amounts of each of these factors will vary somewhat depending on whether your serum had been heat inactivated or not, how fresh the serum was, and how it had been stored, However, all of these factors activate PMN chemotaxis and degranulation. When they are strongly activated, PMN will degranulate and then die. This what you are seeing.
Good luck, RW
Jim,
In normal blood, PMN are not exposed to serum, they are in plasma. Compared to fresh serum, plasma contains very few PMN activators and it contains a host of protease inhibitors. When clotting occurs, platelets, PMN, all granulocytes, most agranulocytes undergo a huge burst of activation and some RBCs may even be lysed. All of the platelets and granulocytes will release their granule contents into the plasma. These granules contain large amounts of potent proteases and a broad range of bioactive compounds. So, freshly prepared serum still contains many or most of these compounds. They can be depleted by heat inactivating the serum or by storing the serum for a period of time. Serum can also be produced from anticoagulated blood or plasma from which cells and platelets have first been removed. This may avoid the generation of many PMN activators.
RW
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