NORTHWESTERN UNIVERSITY 
CHICACO, ILLINOIS 60611 
DEPARTMENT OF MICROBIOLOGY-IMMUNOLOCY 
THE MEDICAL AND DENTAL SCHOOLS 
WARD MEMORIAL BUILDING 
303 EAST CHICACO AVENUE 
May 15, 1979 
Dr. Wallace Rowe 
Building 7, Rm. 304 
National Institutes of Health 
Bethesda, Md. 20205 
Dear Wally, 
Let me respond in the broadest context to your letter of March 22, 1979, asking 
for my comments concerning possible biohazards associated with DNA recombinant 
research employing Escherichia coli. The question as I understand it, is whether colo- 
nization of humans by E. coli synthesizing potentially antigenic eukaryotic proteins 
specified by segments of inserted DNA might elicit immune responses causing injury 
to host cells and tissues which share antigenic determinants with the proteins elaborated 
by the E. coli vector system. 
I do not believe such autoimmune disease is any more of a biomedical health 
concern, with recombinant DNA research os presently envisioned, than disease which 
may result from autoreactive immune responses induced by the prokaryotic microbial 
cells themselves, with which man has lived since time immemorial. In other words, I 
see the eukaryotic proteins secreted by E. coli bearing foreign DNA sequences as no more 
likely to induce autoreactive immune responses than the native antigenic constituents 
of the prokaryotic vector cell itself. And it is in this light that I wish to place my comments 
which follow. 
As all biologists know and microbiologists especially appreciate, host-parasite 
interaction in all of its infinite and endless manifestations is a basic characteristic 
of all living matter. There is every reason to believe that human beings have been 
parasitized by microbes during most if not all of the 3.6 million years man and his 
progenitors have inhabited this planet. We live today as we have always lived, amid 
a miasma of microorganisms of endless variety with varying propensities for parasitizing 
our cells, tissues and organs from the moment we are born until the moment we die. 
Only when we die are we no longer able to serve as a host refuge for the ever-present 
microbial parasites that live on and in us all of our lives. In no organ is this endless 
microbial parasitism better exemplified than the gastrointestinal tract of man and its 
normal microbiota, of which E.coli is an important member. 
[265] 
THE MrCAV MEDICAL CENTER OF NORTHXX ESTERN UNIVERSITY 
