PHOSPHATE GROUP REQUIREMENT FOR MITOGENIC ACTIVATION OF LYMPHOCYTES BY AN EXTRACELLULAR PHOSPHOPOLYSACCHARIDE FROM LACTOBACILLUS-DELBRUECKII SSP. BULGARICUS

The mitogenic activity of extracellular polysaccharides produced by La ctobacillus delbrueckii ssp. bulgaricus OLL 1073R-1 and NCFB2483 was e xamined in murine lymphocytes. The extracellular polysaccharide from L actobacillus delbrueckii ssp. bulgaricus OLL 1073R-1 was fractionated into neutral and acidic polysaccharides by anion-exchange chromatograp hy, while that of Lactobacillus delbrueckii ssp. bulgaricus NCFB2483 w ere all fractionated into neutral polysaccharide(s). The acidic polysa ccharide stimulated mitogenic responses of murine splenocytes and Peye r's patches but not of thymocytes. The optimal concentration of the ac idic polysaccharide at the highest stimulation was 160 mu g/ml. A sign ificant increase of mitogenic activity was initiated at 24 h, and the highest response was obtained after stimulation for 48 h. The acidic p olysaccharide purified by high performance liquid chromatography also had substantial mitogenic activity, and the molecular weight was estim ated to be 1.2 x 10(6). The acidic polysaccharide was a phosphopolysac charide consisting of glucose, galactose and phosphorus. Dephosphoryla tion by hydrofluoric acid degradation reduced the mitogenic activity i n lymphocytes. The phosphopolysaccharide produced by Lactobacillus del brueckii ssp. bulgaricus 1073R-1 is a potent B-cell-dependent mitogen in which the phosphate group acts as a trigger of the mitogenic induct ion. (C) 1998 Elsevier Science B.V.