Erythrocyte ‘Feierzeit’ reaction: Novel filamentous and vesicular response to <i>n</i> ‐butyl acetate

Human erythrocytes (red blood cells; RBCs) undergo spontaneous disassembly after several hours of exposure to n-butyl acetate (nBA). Images of the morphological changes were captured in time-lapse sequences using differential interference contrast (DIC) light microscopy. On exposure to less than 10 mM nBA dramatic events did not take place, but with ∼60 mM aqueous solutions of nBA, discocytes became spherical with a single contiguous 'geographical' indentation patch. Over the next ∼2 h the cells became echinocyte-like with rounded projections; and several hours later they discharged filaments that writhed in Brownian motion. In parallel with these changes, vesicles budded from the cells, followed by their alignment on the filaments, like balloons on a string. The vesicles then serially fused, finally giving rise to a single large vesicle that was ∼0.1-0.2 times the diameter of the spherical parent cell; it then fused with the parent cell that a short while later ruptured and became a 'ghost'. Owing to the striking nature of this phenomenon that was evocative of party decor, the term coined for it was Feierzeit (German: celebration time). The background to this serendipitous discovery, and the deductive odyssey that identified the causative agent, nBA, are presented. Broader implications for understanding the assembly of the RBC cytoskeleton-plasma membrane complexes, and their disassembly under normal, pathological, and forensic conditions are discussed.