Regarding the infectivity of naked DNA

[Ian A. York]

In article <wardp-2305951340410001 at oisin.usask.ca> wardp at herald.usask.ca (Pearse Ward) writes:
>
>The implication from this work is that the immune response generated is
>cell-mediated immunity. Without antigen recognition by CD4+ cells, I don't
>see how this is possible. Therefore, for this system to be working as
>advertised, there must be some explaination as to how the exogenous
>antigen gets presented to Th cells.

CTL can, in some cases, be primed with no contribution from CD4 cells; 
see the references below.  CTL priming is a mysterious process, and I 
believe that sometimes helper cells are clearly required, sometimes they 
are not.  That leaves the naked DNA priming still open.  By the way, I 
believe Ulmer's paper specifically identified CTL specific for the gene 
they injected.

Ian

Rahemtulla A.  Fung-Leung WP.  Schilham MW.  Kundig TM.  Sambhara 
SR. Narendran A.  Arabian A.  Wakeham A.  Paige CJ.  Zinkernagel RM.  et al
Normal development and function of CD8+ cells but markedly 
decreased helper cell activity in mice lacking CD4.
Nature.  353(6340):180-4, 1991

"Here we report that these mice have markedly decreased helper cell
activity for antibody responses, although cytotoxic T-cell activity
against viruses is in the normal range."


Rahemtulla A.  Shahinian A.  Kundig T.  Zinkernagel R.  Mak TW.
CD4 negative mice as a model for immunodeficiency.
Philos Trans R Soc Lond B Biol Sci.  342(1299):57-8, 1993

"A mouse strain without CD4 expression has been generated. These animals,
surprisingly have a normal CTL response and reduced, but not absent,
humoral responses."

-- 
Ian York   (york at mbcrr.harvard.edu)
Dana-Farber Cancer Institute, 44 Binney St., Boston MA 02115
Phone (617)-632-3921     Fax  (617)-632-2627