Floculation
Another
form
of
antigen-antibody
reaction
occurs
if
the
antigen
is
neither
cellular
nor
soluble,
but
is
in
an
insoluble
particulate
form.
Such
is
the
case
with
the
VDRL(Venereal
Disease
Research
Laboratory)
test
used
for
the
diagnosis
of
syphilis.
The
test
makes
use
of
a
hetero
genetic
antigen
shared
between
the
spirochete
of
syphilis
and
normal
beef
heart.
The
antigen
used
is
a
water
insoluble
cardiolipin.
This
antigen,
in
the
presence
of
an
antibody
like
substance
(reagin)
in
the
serum
of
patients
with
syphilis,
forms
visible
aggregates.
The
test
is
commonly
performed
on
a
glass
slide.
