Purification and characterization of streptococcal proliferative factor.

Abstract

Group A streptococcal infections are often associated with scarlet fever and flares of guttate psoriasis. Previous investigation has demonstrated the presence of a factor in streptococcal culture filtrates capable of stimulating proliferation of rabbit keratinocytes in vivo and human lymphocytes in vitro. This report outlines an in vivo method for the production of streptococcal proliferation factor, its purification, and characterization of its physical properties. We cultured Group A streptococci (Type 12, Strain NY5) in synthetic media by in vivo incubation within dialysis casing surgically implanted in rabbit peritoneum. Streptococcal exoproteins were isolated by centrifugation of the bacteria and millipore filtration. Purification of streptococcal proliferative factor was accomplished by differential solubility and molecular sieve was discovered in the resulting product. The relative by SDS gels and molecular sieve chromatography. The sedimentation coefficient determined by sucrose gradient ultracentrifugation is 2.7S. Isoelectric focusing showed minimal microheterogeneity with the pI of the major band being 5.0. Thus, streptococcal proliferative factor can be produced by in vivo incubation of streptococci in synthetic media. Purification entails a rapid 2-step process. The relative molecular weight, sedimentation coefficient and isoelectric points have been established.