The Resistance of the End-piece and Mid-piece of Complement Inactivated by Distilled Water

In I9O 7, Sachs and Teruuchi 1 reported that if fresh guinea pig serum were appropriately diluted with distilled water (optimum relationship, I part serum to 8 to 9 parts distilled water), and incubated for an hour or more in a water bath at 37 ° C., on the restoration of isotonicity, complement activity no longer took place. The absence of hemolysis they attributed to a permanent' destruction of complement, produced, they assumed, by a ferment first becoming active in the diluted guinea pig serum. More recently, however, Sachs and Bolkowska 2 have observed that' at times complement activity may be restored to such inactivated serum on the addition of either fresh guinea pig end-piece or guinea pig mid-piece. This latter observation, taken in connection with recent work 3 on the resistance of the globulin fraction of guinea pig serum inactivated by heat, suggested that perhaps the resistance of one or possibly of both complement fractions might likewise be directly demonstrated in serum rendered inactive by dilution with distilled water. The resistance of the globulin fraction was first examined. The method employed is as follows: A series of centrifuge tubes, each containing one cubic centimeter of guinea pig serum to nine parts of distilled water, was incubated in a water bath at 37 ° C. for one and one quarter hours. Two of these tubes were then made isotonic by the addition of sodium chlorid and used as controls, their contents being directed against * Received for publication~ April 20, I9II.