In article <346009C9.1C33 at licre.ludwig.edu.au>, davis at licre.ludwig.edu.au wrote:
> Mark Doherty wrote:
> > In article <34570F99.2F7A at mail.cyberlink.bg>, anastas at mail.cyberlink.bgwrote:
> > > Does anyone out there know whether monocyte derived (+GMCSF/IL-4) DC
> > > remain still DC if one removes BOTH cytokines from culture after n days?
> >
> > The short answer is yes. The DC are terminally differentiated.
>> The correct short answer is "no!" If you remove the IL-4, they promptly
> sit down and look just like monocytes again. I'm quite sure they're not
> terminally differentiated.
They still remain class 2 high, and birbeck granules are observable for at
least a couple of days after removal of IL-4 (more than a couple of days
and it's hard to say with the generation of new cells plus the senescence
and death of older cells in culture). They do decrease expression of VCAM
and ICAM, which is why they don't look "spiky" any more, but they don't
regain phagocytic ability and remain resolutely acid phosphatase
low/negative. I don't think they could be called macrophage/monocytes.
The same is true with differentiated macrophages, too - after
differentiation in MCSF or GMCSF, treatment with IL-4 increases the
expression of adherence molecules and you get the typical, almost
fibroblastoid shape (IL-13 does exactly the same, and we have some nice
pictures in our JI paper about 3 years back). If you remove the IL-13 or
IL-4, they eventually settle down - but they don't seem to revert to
monocytic forms.
Actually, I don't know of any evidence that these cells - once they gain
characteristic DC properties - go back to a monocyte-like stage, although
Steinman's group have shown that there is a pretty fine line in the other
direction from monocyte-like to DC. Still, I could have missed this -
references anyone?
Cheers, Mark
