35
Reformatsky and Levi (quoted p. 345 of Mellor's Chemical Statics) have
shown that the velocity of a chemical reaction is not lessened when the viscosity
is increased by gelatine, agar or silicic acid. Still, whatever the cause, increase
of viscosity in this case was accompanied by less lysis. Small quantities of both
egg-albumin and gelatine in the mixture were accompanied by a higher degree of
lysis than when salt alone was present.
TABLE No. 16.
No.
Viscous medium.
Percentage in
mixture.
Concentration
of complement.
L y s i s .
1
...
...
...
Heated sheep serum...
per cent.
0.04
Complete.
2
Dextrin
......
5.0
„
0 .06
3
4
Gum arabic
...
...
...
...
...
0.85 per cent. NaCI control
...
...
...
3.2
„
0 . 0 8 8
0.13
,,
5
Gum arabic
...
...
...
...
...
5.0 per cent.
0.22
Not complete.
6
Do.
...
...
...
...
6.4
„
0.22
, ,
7 i Dextrin
...
...
...
...
...
13.0
„
0'22
, ,
S
Do.
...
...
...
23.0
,,
0 . 2 2
Partial.
Viscosities of
, ,
,,
2 & 3
5 & 7
6 & 8
<viscosity
=
,,
>
,,
1
1
1
Table No. 16 shows, like Table No. 15, that the higher concentrations of
viscous substances such as dextrin and gum arabic tend to interfere with lysis,
whereas low concentrations such as 5 per cent. and 3.2 per cent. appear to favour
lysis even more than simple admixture of 0.85 per cent. salt. On this occasion an
increase of lysis was found in the presence of 65 per cent. heated sheep serum.
This cannot have been due to added amboceptor, as normal sheep serum contains
no isolysin for sheep cells : nor was it due to insufficient heating, for controls
showed that it contained no complement. No explanation will be offered at this
moment.
If the inhibition by heated serum were, as a rule, clue to complementoids
blocking the union of complement with amboceptor, one would expect the effect
to be the more marked the better opportunity the complementoids have, i.e., if
additional heated serum containing complementoids were incubated with sensitized
RBCs before adding complement, one would expect more inhibition of lysis than
if the complement were added immediately. This however does not prove to be
the case, so if the inhibition of heated serum is clue to complementoids they have
such an affinity for the amboceptor that they can block it quickly in presence of
complement.
Another explanation may be that any possible blocking of the complement-
ophile group of the amboceptor of sensitized cells that can occur has already
taken place in the process of sensitization, so that the subsequent exposure to
heated serum after washing the sensitized RBCs has no effect.
When 1 . 5 times the full dose of complement for a particular degree of
sensitization was present 25 per cent.—50 per cent. of heated serum in a mixture
inhibited the lysis of sensitized RBCs partially ;
When 0.75 full dose of complement was present
—
25 per cent.—5o per cent. of heated sheep serum likewise inhibited lysis.
10 per cent.—12 per cent.„
had no effect.
,,
, ,
3 . 7 5 per cent.—7.5 per cent. of heated sheep serum increased lysis.
less than
3.75 per cent.
„
,,
had no effect.
77
So, while large quantities of heated sheep serum inhibit lysis, small quantities
have an adjuvant or auxilytic effect.
Serum decomplemented by heated RBCs, so that no complement which
can become complementoid remains, still inhibits, when heated, just like unde-
complemented heated serum ; so the inhibitory power cannot be due to comple-
mentoids.
The presence of heated serum even in large quantity has no influence in
preventing the union of amboceptor and RBCs ; the RBCs are sensitized just as
completely as when suspended in salt.
E-I