Fig. 3. The quantity of exosome secretion changes following heat stress. Exosomes were purified from culture supernatants containing equal numbers of control or 3-hour heat-stressed cells [IB4, BLCL(LL), BLCL(PC) or Jurkat cell lines]. The exosome pellet of each purification was resuspended in 100 µl PBS, and total protein determined by BCA assay. The graph represents the ratio of control exosome-protein to heat-shock-exosome-protein, where a ratio of 1 (dotted line) would indicate no difference. (Mean ratio±s.e.m. of n purifications.) The overall mean ratio was 1.245±0.07 (n=20), indicating a small elevation (less than 1.3-fold) in exosome secretion due to stress.