MYCOPLASMA IN THE SPOTLIGHT OF AIDS - PARTIAL BIOCHEMICAL-CHARACTERIZATION OF MYCOPLASMA-DERIVED COMPONENTS INDUCING TNF-ALPHA SECRETION AND BLAST-TRANSFORMATION

We have previously demonstrated that the AIDS-associated Mycoplasma fe rmentans as well as Mycoplasma capricolum membranes activated bone mar row macrophages to secrete tumor necrosis factor a (TNF alpha) and ind uce blast transformation of splenic lymphocytes. Herein, we show that the membrane component of Mycoplasma capricolum capable of inducing TN F alpha secretion is a hydrophobic protein. This is supported by our f indings that the TNF alpha inducing activity was eluted by a phenyl-Se pharose column in a peak distinct from bulk membrane lipids. The hydro phobic nature of the protein is indicated by the activity of the ''hyd rophobic protein'' fraction of the membranes, and the pattern of eluti on obtained by the phenyl-Sepharose column. Fractionation of the M. ca pricolum membranes, solubilized by CHAPS (3-[(3-cholamidopropyl)-dimet hylammoniol]1-propane sulfate) on a gel filtration column revealed a m ajor peak of TNF alpha inducing activity of about 75,000 daltons, and a minor peak of about 55,000 daltons. The mitogenic activity, though s pread throughout the column, peaked in the same fractions as the TNF a lpha inducing activity. Both activities co-eluted by the phenyl-Sephar ose column as well. However, the mitogenic activity of the membranes w as much more resistant to elevated temperatures and extreme pH treatme nt.