36
The inhibitory effect of the heated serum cannot be due to the deviating
action of a precipitum. Precipitin in the mixtures used in our experiments would
be found in the heated anti-sheep serum, and, even if this clung to the sheep RBCs
sensitized in it after washing, such a minute amount would be conveyed into the
mixture that its effect would be negligible. Precipitinogen in large quantity would
be supplied by the heated sheep serum. It was found moreover that washing
the sensitized RBCs even six times made no difference in the amount of lysis.
When washed guinea-pig RBCs 0.05 cc are treated with fresh horse serum,
concentration 20 per tent. in mixture, "Slight" lysis (30 per cent.) results. If
heated goat serum is present in the mixture in concentrations of-
50 per cent. " complete " lysis results.
17.5 per cent. " partial" lysis results.
If the guinea-pig RBCs are previously sensitized in equivalent quantities
of heated goat serum and washed, no more lysis occurs than with the fresh horse
serum alone.
So four deductions are possible-
(i) that heated goat serum does not sensitize guinea-pig RBCs ;
(2) that heated goat serum does sensitize guinea-pig RBCs, but that
fresh horse serum is not a suitable complement ;
(3) that the sensitization only occurs in the presence of the complement ;
(4) that there is some substance in the heated goat serum that favours
lysis of guinea-pig RBCs by fresh horse serum. Fresh goat serum by itself lyses
the guinea-pig RBCs actively so (1) cannot be true unless (3) is also true.
On another occasion guinea-pig RBCs previously sensitized in heated goat
serum (A) gave almost precisely the same degrees of lysis with fresh horse serum
(15 per cent.) as they did without sensitization.
When an equivalent quantity of heated goat serum was present in the
mixture, 15 per cent. fresh horse serum gave " complete " lysis and 5 per cent.
"slight" lysis ; and when the, presumably, deśensitized heated goat serum (A)
was used in place of unextracted heated goat serum 15 per cent. fresh horse serum
again gave complete lysis, but 5 per cent. gave no lysis. Apparently, therefore, a
part of the substance which aided lysis was extracted from the heated goat serum
- by the guinea-pig RBCs and this must have been amboceptor.
The conclusion arrived at is that sensitization of heterogenous RBCs by a
normal heatea serum does not occur readily, but that if the heated serum is
present with complement in a hæmolytic sustem sensitization does take place.
Guinea-pig RBCs, sensitized in either heated horse serum or heated goat
serum and washed, are complemented to a certain extent by fresh guinea-pig
:serum, but lysis is only slight to partial,.
Each tube containing a total of 2 cc of liquid,
Fresh
,,
,,
,,
horse
,,
, ,
,,
serum
,,
,,
,,
15 %+
15 %+
15 %+
15 1 +
Nil.
5 %
15 0/0
50 %
Lyse
„
,,
,,
0 . 0 5
„
,,
,,
guinea-pig RBCs
,,
,,
,,
Slight.
Partial.
Not complete.
Complete.
Fresh
„
,,
guinea-pig
, ,
serum
,,
,,
so that 6 parts of horse serum , contain enough amboceptor for complete lysis of
one part guinea-pig RBCs when more than 6 and less than 20 parts fresh guinea-pig
serum (complement) are available.
From another experiment the following excerpt is made :—
TABLE No. 17.
A . Fresh sheep serum ...
Salt 0 •85 per cent. ...
Rabbit RBCs
...
. . .
. . .
...
. . .
...
. . .
•••
...
...
•••
...
...
0.35
1.6
0.05
Lysis COM-
plete 1 0 0
per cent.
B. Fresh guinea-pig serum
Salt ....
...
..
Rabbit RBCs
...
...
...
...
. . .
...
...
.
...
. . .
0.25
1.7
0.05
Slight.
20 per cent.
C. Heated sheep serum
Fresh guinea-pig serum
.
...
Salt .... .
Rabbit RBCs
...
...
...
...
...
...
...
...
...
...
...
...
. . .
. . .
. . .
1.0
0.25
0.7
0.05
Not complete.
80 per cent.