12
a fluid coloured by hæmoglobin. Thus heated RBCs may be used to extract
amboceptors from different heated serums, and their sensitization made evident by
their power of abstracting complement from other serums. Whenever complement
is thus abstracted lysis would have occurred if the RBCs had not been heated.
Horse serum does not lyse man RBCs. Sensitization of man RBCs by
horse serum cannot be demonstrated, and so horse serum treated with man RBCs has
no complement abstracted from it. Horse serum does, however, lyse guinea-pig
RBCs slightly, and treatment of horse serum with washed guinea-pig RBCs
results in slight lysis, and the consequent abstraction of complement from the serum
can easily be demonstrated.
(8) There seems to be no limit to the number of amboceptors which can be
present normally in a serum, though some serums contain more, some less and some,
such as horse, scarcely any at all. For example we were able to extract from the
same 20 cc of heated dog serum in succession the following sensitizers : man, rabbit,
guinea-pig, goat, sheep, horse and man, and to demonstrate in each case, on the
one hand, the sensitization of the RBCs by complementing with fresh guinea-pig
serum and, on the other hand, the absence of much more of that sensitizer from the
dog serum by means of the addition of a fresh portion of the RBCs in question
together with guinea-pig complement. Compared with an immune serum, which
results from the injection of a foreign serum or foreign RBCs, a normal serum is
remarkably deficient in sensitizer for heterogenous RBCs; but there is great
variation among individuals in this respect. As a general rule a normal serum
which is potent against one kind of RBCs is potent against all, and one which is
weak against one is weak against all; but the variations exhibited from time to
time in the lytic power of a serum for one kind of RBCs are not necessarily accom--
panied by variations in the same direction for others.
Sheep serum, for instance, which was largely used in the course of numerous
experiments for several years, was found to vary considerably in its relative lysin
content for the seven kinds of RBCs generally used; that is to say, if the quantity
of lysin present for man RBCs is large, it does not follow that the lysin for rabbit
RBCs is also large, and vice versâ. No relation can be made out between the
variations in the quantities of the different lysins from time to time. Vide Chart
No. 3.
It may be that plurality of amboceptors has some relation to diet and that the
species whose diet includes the widest range of proteins has naturally the most
diverse store of antibodies in its blood.
We thought it possible that the resistance shown by the RBCs of different
species to hypotonic lysis might be related with their resistance to lysis by normal
serums, but the large number of data collected do not lend support to this view.
Endeavours to arrange RBCs according to their resistances to coagulation
by heat failed, as mentioned before, owing to time not permitting a sufficiently
delicate method of measurement being devised, though there were certainly
indications that this order corresponded in some degree with their resistance to
hypotonic lysis.
A number of experiments made it seem probable that some relation also
exists between the specific gravity of RBCs and their resistance to hypotonic lysis,
though here again we failed to elaborate a method of sufficient accuracy in the time
which could be devoted to it.
The specific gravity as determined—
(a) by rate of subsidence in isotonic salt solution;
(b) by rate of subsidence in 10 per cent. and 15 per cent. cane
sugar solutions.
The approximate relative specific gravity of the RBCs tested is shown
below :—
Sheep
1.0
Goat
1.0
Dog
1.41