MEMBRANE PHASE-TRANSITION OF INTACT HUMAN PLATELETS - CORRELATION WITH COLD-INDUCED ACTIVATION

Using Fourier transform infrared spectroscopy (FTIR), we have determin ed the phase transition temperature (T-m) of lipids in intact human pl atelets and have shown that it occurs between 15 and 18 degrees C, the temperature at which cold activation of platelets has previously been reported (Zucker and Borrelli, 1954, Blood, 28:602-608; White and Kri vit, 1967, Blood, 30:625-635). The temperature at which the platelets pass through T-m is highly correlated with initial platelet shape chan ge. However, shape change continues after the cells have passed throug h the phase transition. Cold-induced activation has previously prevent ed long-term storage of platelets at 4 degrees C. Antifreeze glycoprot eins (AFGPs) isolated from polar fishes previously have been used to p revent ice crystal growth during freezing of tissues as well as leakag e of solutes from liposomes as they were chilled through their T-m. We sought to determine if these AFGPs were able to stabilize platelets f or long-term storage at 4 degrees C. Incubating platelets with antifre eze glycoproteins during long-term storage and rapid rewarming to 37 d egrees C abrogated granule secretion associated with cold activation i n a dose-dependent manner. This work suggests that AFGPs may be a poss ible solute for use in long-term low temperature Storage of platelets. (C) 1996 Wiley-Liss, Inc.