A simple method for extracting human lymphocyte stimulants from human dental plaque bacteria of the genus Actinomyces.

The effect of acid concentration on the hot-acid extraction of antigens from Actinomyces viscosus that stimulate human peripheral blood lymphocytes in vitro was tested. The optimum pH for release of these antigens in a soluble low molecular-weight form was pH 2.3. Preliminary purification on Sepharose 4B demonstrated that most of the lympho-stimulatory material (about 90 per cent) had a mol. wt of about 100,000. This partially-purified antigenic material was mainly protein. The pH 2.3 hot-acid extraction was also suitable for extracting antigens that stimulate cellular immune responses from three strains of Actinomyces naeslundii and 1 strain of Actinomyces israelii, but did not release lympho-stimulatory material from Streptococcus sanguis which is a poor human peripheral-blood lymphocyte-stimulant and was used to demonstrate that the hot-acid extraction is not simply extracting a mitogenic macromolecule common to all bacteria. As good yields of soluble, biologically-active antigens were obtained from all of the Actinomyces, the procedure described will facilitate the purification and characterization of these antigens.