x
take place. Bordet-Gengou observed that a mixture of any antigen and antibody when com-
bining has the property of fixing complement. Substances which give rise to the production of
antibodies (antisubstances or immune bodies or amboceptors) are called antigens, examples of
which are toxins, ferments, molecules of tissue cells, bacteria and red corpuscles, etc. Anti-
bodies are the products of antigens Thus a culture of cholera vibrios is an antigen and serum
from a patient suffering from cholera contains the specific antibody. According to these observers
a mixture of cholera culture and anti-cholera serum, when added to a haemolytic system as
above described, will fix the complement present and prevent the lysis of the corpuscles taking
place. From these observations upon fixation of complement Wassermann saw that it would be
possible to determine the presence of either antigen or antibody in a given fluid. In short if an
antibody is present, the addition of antigen in the presence of a complement containing hæmoly-
tic system will lead to the fixation of the complement and prevent lysis taking place. If the
same is absent, complement will not be fixed and lysis will take place. So that it comes to this
that if a syphilitic antigen is available, the presence or absence of the syphilitic antibody in a
blood may be easily found out. In this test the hæmolytic system is simply used as an indi-
cator, as it can readily be seen whether lysis has taken place or not-
will give no lysis, as the compound of antigen and antibody has fixed the complement. But if
instead the serum of a normal healthy man is used complement will be free to produce lysis. As
spirochaeta pallida cannot be cultivated in a laboratory, Wassermann used a saline extract of
the dried liver of a congenitally syphilitic foetus, rich with this parasite, for antigen.
It was subsequently pointed out that the Wassermann reaction for syphilis was of an order
distinct from that of Bordet-Gengou. Noguchi and Levaditi have obtained similar results by
using in the place of Wassermann's syphilitic antigen (1) an alcoholic extract of a normal organ,
(2) lecthin, (3) soluble soaps, (4) bile salts. They have therefore come to the conclusion that it
is a lipoid. reaction. As syphilitic serum differs from normal in the relative abundance of glo-
bulins it contains, it has been suggested that lipoids added to syphilitic serum combine with
these abundant globulins to form an antigen-like body which in joining with the immune
bodies present in the serum, bind the complement of the guinea-pig's serum present in the
mixture.
There are several variations in the way of carrying out the serum test. Chief among these
are (1) the original method as adopted by Wassermann, (2) a modification by Hecht-Fleming
and (3) a modification by Levaditi. In the original method Wassermann used a saline extract
of dried syphilitic liver as antigen. Specimens of livers from macerated fœtuses are received
from the Maternity hospital from time to time. These are divided into one large portion wrapped
in sterile gauze and preserved in ice and another small bit put in 10 per cent. formaline.
T h e l a r g e r b i t , o n r e c e i p t , i s f i n e l y m i n c e d , s p r e a d i n t h i n l a y e r s i n s t e r i l e p e t r i - d i s h e s l a b e l l e d a n d
put in large desiccators over quicklime for drying. The smaller bit is carried through several
reagents as per Levaditi's silver nitrate method of staining spirochaetes and is cut into sections.
If on examination the section reveals spirochaetes, the corresponding desiccated portion of the
liver is used for making the saline extract used as antigen in the test.
The reagents used in this method consist of
—
(1) Serum of patients suspected to be syphilitic. — About 2 to 2½ c. c. of peripheral blood can
be easily collected in one or two Wright's capsules. A free supply of blood is promoted by-
(i) Swinging the arm rapidly round at the shoulder until there is a feeling of heaviness
at the tips of the fingers.
(ii)
Bandaging the finger with a handkerchief, tightly enough to prevent venous
return but not to check arterial circulation.
(iii)
Giving a good prick with a triangular surgical needle; such a puncture yields a
better supply than that made by an ordinary needle.
(iv)
The finger should previously have been cleaned with sublimate lotion followed by
alcohol.
In certain persons of deficient vitality it is sometimes impossible to get sufficient blood by
this means. A small cut with a lancet or razor may have to be resorted to and this is less pain-
ful than the prick with a triangular surgical needle. The capsules should then be placed in an
upright position in a cool place and not shaken for at least an hour, in order to let clear serum
separate out. In sealing the capsules it is essential that the blood be not heated, so it is
perhaps better to use sealing wax rather than to try and melt the glass. The blood is then
transferred to a centrifuge tube and centrifuged serum is collected in a glass capsule which is
sealed and put into a water-bath at 56° to 57° C. for half an hour to destroy any trace of comple-
ment present in the serum.