I have been reading the correspondence on ADV with interest and some
growing concern that ignorance of disease processes and testing procedures
is beginning to seriously cloud the issue.  I've been holding off trying
to give a brief overview of immunology on the list, but I think it may be
useful if a few fundamental points were made at this time.
 
Firstly, antibodies are NOT a part of the disease organism.  They are
proteins synthesised by certain of the patient's white blood cells (B
lymphocytes) in response to a disease organism, and in most cases react
only with a SPECIFIC structure (often a part of another protein) present
on that particular disease organism.  The antibodies are designed to
inactivate the disease organism, and/or to signal to other white blood
cells to remove from the body the disease organism to which the antibodies
have bound.  Different B lymphocytes produce different antibodies, each
with a specificity for a particular structure on a particular disease
organism.
 
Antibodies are an integral part of the body's response to infection, and
are a desirable part of the immune response.  Certain types of antibodies
can cross the placenta of the mother to provide protection to young in
utero, but these disappear from the babies' bodies with weeks to months
after birth.  Another class of antibodies are provided in mothers' milk,
but again they disappear with weeks to months after suckling stops.
Antibodies CANNOT be transmitted through more than one generation of
mammals, and no immunologist would consider that antibodies are passed
from father to offspring.
 
The presence of antibodies is taken by scientists to indicate that the
tested animal (or person) has been exposed to the disease organism with
which the antibodies are designed to react.  The disease organism's
proteins to which antbodies bind are referred to as 'antigens', although
sometimes the whole organims itself may be termed an antigen.  If a test
is manufactured containing a sample of an antigen belonging to a disease
organism, and antibodies from a patient's blood react to this antigen, then
it is assumed that the patient has previously been exposed to the relevant
disease organism.  This assumption is fallible though, as will be indicated
in the posts to follow.
 
Harko Werkman,
Frog Research Group,
Department of Biological Sciences,
University of Newcastle,
Callaghan,
NSW. 2308.
Australia.
Ph: (+612) 4921 6253
Fax: (+612) 4921 6923
Email: [log in to unmask]
[Posted in FML issue 2954]