Phospholipids and Complementary Activity

Abstract

In a previous communication,¹ it was demonstrated that prolonged extraction of active, dehydrated complement with organic solvents, i. e., alcohol, ether, etc., resulted in no reduction of complementary activity. In fact, the recovered lipids often exhibited anticomplementary properties when returned to the extracted residues prior to titrations.

Recently, Bloor and Snyder² have noted that a buffered suspension of oxidized phospholipids oxidizes a sensitive methylene blue preparation.

In view of earlier work from this laboratory,³ which revealed an intimate connection between complementary powers and oxido-reduction phenomena, it was decided worthwhile to study the effect of oxidized and unoxidized cephalin and lecithin on complementary activity.

Purified preparations of the 2 phospholipids were employed throughout these experiments. The oxidized phospholipids were prepared according to the technic of Bloor and Snider and complement was titrated by the method advocated by Ecker, Pillemer, Wertheimer and Gradis.⁴

The amounts of reagents employed and general procedures are found in the accompanying protocols. All solutions were prepared in a M/15 phosphate buffer pH 7.2.

The experiments of Bloor and Snider were repeated and confirmed. As reported by these authors, it was also found that phospholipids do not oxidize a sensitive preparation of reduced methylene blue, while the oxidized lipids show a definite oxidizing power.

Various portions of the phospholipids were then added to fresh guinea pig complement, and their effects noted. Table I shows the relative inhibitory effect of the various phospholipids on complement.