RE: CD4-CD8- T cells in pediatric AIDS

Hello
Yes, don't worry, these cells are real!
The following is "off the the top of my head" - ie from memory, so one
should	check out my info. So, with that caveat, here goes!
If you analyse these cells for CD56/CD16 you should find them to be
positive. These, then are known as "natural-killer like" cells - in that
they express CD3 unlike "true" NK cells. Morphologially you seem to be
describing LGL's - which would fit with the immunophenotype described. (As
an aside, you may wish to look at the CD45RA/CD45RO and TCR a/b and d/g
expression of these cells).
In my experience in a paedriatric unit in Sheffield we saw a number of cases
with relatively high NK-like populations. In addition, some severely
immunocompromised patients, from HIV, SCID, etc show increased NK-like
levels. Also, as with NK's, NK-like levels have been reported increase in
old age. NK and NK-like leukaemias are both extremely unpleasant with poor
prognosis.
Significance? Well, a Google will help 'cos there's a lot of info out there!
But one theory is that NK-like cells form a "compensatory" mechanism which
may ameliorate the effects of immune deficiency in severely
immunocompromised cases.
Hope this helps.
Mark Simmerson
Technical Specialist - Auckland 
> -----Original Message-----
> From: Calin Tatu [SMTP:dns@mail.dnttm.ro]
> Sent: Tuesday, 13 January 2004 09:26
> To:	Cytometry Mailing List
> Subject:	CD4-CD8- T cells in pediatric AIDS
> 
> Hi!
>  
> We are consistently finding a double negative (i.e., CD4-CD8-) population
> of T cells in most of our cases of pediatric AIDS and we have some
> difficulty in explaining the origin and nature of this population. In
> certain cases these cells can make up to 7-8% of the total number of CD3
> cells from the peripheral blood. They seem to be some large lymphocytes
> expressing high levels of cell surface CD3. We have invariably seen this
> population using CD4/CD8 antibodies from different sources, so a staining
> artifact would be unlikely. Any input would be appreciated!
> Thanks a lot for your help,
> Calin.
>  
>