In article <Pine.SOL.3.91.970503145644.18869A-100000 at gort.canisius.edu>,
geoff bernas <bernasg at GORT.CANISIUS.EDU> wrote:
>>What then do NK cells recognize on the surface of target cells which
>allows the lyses of some cells, but which prevents the lyses of others?
Over the past few years, this has suddenly changed from a mysterious
subject with a little speculation, into an enormous, rapidly growing, and
well-researched field. The brief summary is that NK cells seem to have a
series of receptors which recognize MHC class I molecules, and which
(usually) deliver an inhibitory signal; thus normal cells with high MHC I
are usually not lysed. The positive signal isn't quite as clear, but is
at least partly cell adhesion molecules. As a brief and misleading but
nevertheless snappy slogan, NK cells kill as their default option and
require inhibitory signals not to kill, while CTL are harmless as their
default and require positive signals to kill.
Ian
--
Ian York (iayork at panix.com) <http://www.panix.com/~iayork/>
"-but as he was a York, I am rather inclined to suppose him a
very respectable Man." -Jane Austen, The History of England
