THE OCCURRENCE DURING ACUTE INFECTIONS OF A PROTEIN NOT NORMALLY PRESENT IN THE BLOOD : II. ISOLATION AND PROPERTIES OF THE REACTIVE PROTEIN.

Methods are described for isolating a protein commonly present in the blood of patients during the acute phase of various infections which, unlike the normal serum proteins, is precipitable by the C polysaccharide of Pneumococcus. The reactive protein is present in the fraction of serum albumin precipitated by either ammonium or sodium sulfate between 50 and 75 per cent saturation. From this fraction the reactive protein separates out on dialysis against tap water. Following removal of the alcohol-ether-soluble lipids from acute phase serum the reactive protein becomes soluble in tap water, and is no longer precipitable by traces of calcium but still retains its precipitability with the C polysaccharide.