Â鶹´«Ã½

From David Hume, University of Queensland

I read with interest the article by Nektarios Tavernarakis on cell death (15 February, p 30).

This is certainly a fast-moving field, in which genetic studies on model organisms such as Caenorhabditis elegans and drosophila have given us fundamental insight.

Yet the author is incorrect when he refers to necrosis not being described until about 15 years ago. The distinction between apoptosis and necrosis in mammalian systems was recognised by researchers such as John Kerr and Andrew Wiley at least 10 years earlier.

The author is also incorrect in saying that after apoptotic cells die they are gradually dismantled and assimilated into surrounding cells. The main purpose of apoptotsis is for the cell to become a bite-sized morsel that can be engulfed by another cell and digested. Mammals have professional “undertaker” cells, the macrophages, to perform this function.

The really interesting question is how the undertakers can sense a dying cell from a distance, and recognise that it must be eaten. There are a number of recent publications dealing with the nature of the “eat me” signal.

One key difference between apoptosis and necrosis is the failure in the latter case of a process that would normally permit the orderly removal of the corpses of the dead.

Brisbane, Queensland, Australia