29'
Sheep RBCs generally have not been able to fix much more of our Goat B
antisheep sensitizing molecules than they require for the optimum combination.
We found that 2 . 6 cc. of heated goat B serum on one occasion gave the maximum
degree of sensitization obtainable with 10 cc. washed sheep RBCs, using fresh
sheep serum in excess as complement. When up to 4 . 5 times that quantity of
sensitizing serum was used, no further sensitization occurred, as shown by an
increased range of lysis with diminishing quantities of complement, nor was any
trace of deviation noticed when the quantity of complement remained at the
previously found optimum.
Working with Goat K antisheep serum another method was tried. Instead of
sensitizing RBCs in varying quantities of the immune serum, mixtures were made,
each cont ai ni ng 1 cc. of f r esh Goat K ser um and i ncr easi ng quant i t i es of heat ed
goat K serum, and series were put up with these mixtures. The several mixtures
contained diminishing amounts of complement and increasing amounts of ambocep-
tor. Even when the relation of amboceptor to complement was as 8 to 1 no
deviation occurred and the degree of lysis resulting appeared to vary inversely as
the quantity of complement present.
The matter may be rendered clearer if put into tabular form. Let us assume
that RBCs sensitized with
—
part amboceptor require
∞
complement for complete lysis.
2 parts
,
,
,
3 ,, ,
4 ,, ,
5 ,
6 „
7 ,,
8 ,,
9 ,,
I o
„
, , , , , ,
,,
,
,
, ,
,,
, ,
, ,
5 4 3 3 3 3 4 5
, , , , ,
,
,,
, ,
, ,
, ,
, ,
,,
, ,
,
,,
, ,
, ,
, ,
,,
The combination of 5 amboceptor 3 complement is what has been alluded to
as the optimum combination which secures the optimum degree of lysis. More
amboceptor still requires 3 parts of complement, but less amboceptor requires
more complement.
Supposing that the RBCs can fix from 5 to 8 parts of amboceptor and still
show complete lysis with 3 parts of complement, the range of the minimum active
dose of complement, namely 3, is from 5—8 parts amboceptor, and lessening the
dose of complement will lessen the degree of lysis whether the RBCs have fixed 5
or 8 parts of amboceptor.
If the RBCs cannot fix more than 8 parts amboceptor no deviation will be
demonstrable with the minimum active dose of complement. If on the other hand
the RBCs can absorb more than 8 parts of amboceptor, they will become "super-
sensitized", as it has been named, and will require more complement for complete
lysis than the previously minimum active dose. If only that minimum dose is
available, it will be insufficient for complete lysis, and less than complete lysis or
" deviation " will be shown.
There is a strict limit to the amount of amboceptor which RBCs will absorb
from a given serum; but, if deviation is not demonstrable, there is no means of
telling whether RBCs have absorbed more than is required for complete lysis with
the minimum active dose of complement, except by finding how much available
amboceptor is left in the serum.
To return to Goat B antisheep serum, in one experiment we took 10 cc. heated
B serum and sensitized in it, in successive lots, for equal periods of time,
1 cc. washed sheep RBCs
B 7 CC.
, ,
,,
1 cc.
,
, ,
With A o . o23 cc. complement gave partial
lysis.
,,
B
, ,
,
,
complete „
,,
C
„
,,
„
complete „