21
which has been allowed to clot, when the defibrinated serum is used immediately it
can be prepared and the serum from the clot directly a sufficient quantity has sepa-
rated. Serum which is obtained from blood drawn the previous day and allowed to.
clot, even though kept in the ice box in the interval, is generally found to be less
potent than serum obtained from defibrinated blood and used immediately. The loss
of lytic power is not, however, necessarily proportionate for all kinds of RBCs
that may be tested. The following table shows the relative amounts of lysis in one
e x p e r i m e n t : —
TABLE No. 5.
Man serum (defibrinated)1 ½
hours old.
Man serum (clotted)
24 hours in ice box.
Rabbit
Guinea-pig
Hen
,,
H orse
RBCs
„
,,
...
. . .
...
•••
•••
•••
...
.
...
...
...
•••
...
••.
...
Lysis = 1.0
„ = 1.0
„
= 1.o
,
= 1.0
Lysis = 1 . 0
„ = 0. 8
„ = 0 . 6
,, = 0. 4
The serum had not demonstrably lost any lytic power against rabbit RBCs
by being kept for 24 hours, but had lost against guinea pig, hen and horse in
increasing amount. Assuming that there had been no appreciable loss in ambocep-
-tors this result argues in favour of plurality of complements, man complement for
horse RBCs showing itself to be more than twice as labile as man complement for
rabbit RBCs. Another experiment with goat serum gave similar results.
TABLE No. 6.
Goat serum (defibrinated)
2 hours old.
Goat serum (clot)
24 hours in ice box.
Horse
RBCs
Rabbit
Man
,,
Guinea-pig „
Hen
•••
...
•••
...
•••
...
...
•••
•••
•••
...
...
•••
...
•••
...
...
•••
...
Lysis = 1.0
„ = 1.0
„ = 1. 0
„ = 1. 0
„ = 1.0
Lysis = 1.0
„ = 0. 8
,,
= 0.7
„ = 0.6
,,
= 0. 6
*
*
*
.*
(2) To show whether the failure of certain normal serums to lyse foreign RBCs
is due to want of amboceptor or of complement.
This is by no means so easy to demonstrate as would at first sight appear
owing to the unavoidable introduction into the experiment of factors which interfere
with lysis, the nature of which is not clearly understood, such as Ehrlich's so-called
complementoids, and to the peculiar quantitative relationship between amboceptor
and complement. For example sheep serum is not very potent against either horse
or hen RBCs : on an average 15 parts are required to lyse completely 1 part of horse
RB Cs, and 7 parts to lyse i part of hen RBCs.
One might suppose that, if 15 parts of fresh sheep serum lyse 1 part of
horse RBCs, previous sensitization of horse RBCs in heated sheep serum would
lead to more lysis by that quantity of fresh sheep serum if sheep serum is deficient
in amboceptor for horse RBCs. As a matter of fact horse RBCs thus sensitized
are less strongly lysed by sheep serum than unsensitized RBCs, and for this
several explanations suggest themselves, (1) that the complementophile group is
blocked by the complementoids of the heated horse serum, (2) that the strong,
agglutination which occurs interferes with lysis, (3) that the RBCs are supersensi-
tized for the complement available and that deviation occurs.
Using hen RBCs instead of horse we find that previous sensitization in
heated sheep serum enables fresh sheep serum to lyse them more strongly than
unsensitized hen RBCs. In trying to explain this effect we meet the difficulty of
the balance between varying quantities of amboceptor and complement. Within
certain limits the more amboceptor available the less complement is required for
lysis, and conversely ; so in the instance under discussion we can only say that, if
sheep amboceptor for hen RBCs is deficient, the extra sensitization enables the
surplus complement present to cause lysis, and that, if complement is deficient in
the sheep serum the extra sensitization enables the quantity that is present to do
more work.