Reduced antitumor and immune-adjuvant activities of the sub-cellular fractions from Group A Streptococcus.
The sub-cellular fractions from Group A streptococcus (Su-strain) were prepared, and their antitumor and biological activities were examined. The cell wall fraction (CWF) and the protoplast membrane fraction (PMF) were slightly effective in retarding the growth of Ehrlich ascites carcinoma in outbred ddY mice when either fraction was used in combination with 5-FU. The cytoplasmic particle fraction (CPF) and the cytoplasmic soluble fraction (CSF), however, were not effective. In the B6D2F1 mice-L 1210 leukemia system, none of the subcellular fractions were beneficial even when combined with 5-FU. Further, the antitumor effect of OK-432 was completely abolished by disruption of the preparation, indicating that antitumor activity of OK-432 may depend on the structural integrity of the cocci in the preparation. Despite the general lack of anti-tumor activity in the mouse systems, the subcellular fractions, including those of OK-432, inhibited the growth of Yoshida sarcoma cells in culture and the uptake of [2H]-UR and [3H]-TdR by L 1210 cells in vitro. The immunopotentiating activities of these fractions, however, were demonstrated to be markedly diminished as compared with those of OK-432 and heated Su-cocci (60 degrees C, 30 min). The present study, therefore, shows that the decreased antitumor activity of the subcellular fractions closely correlate to the decrease of their immunopotentiating activities.