The amino-acid and elemental composition of a hydrolysate based on lactic-acid bacterial cultures has been studied. The quantitative content of amino acids in the hydrolysate is determined and the analytical method is validated with respect to linearity, reproducibility, and accuracy. Investigation of the biological activity of the hydrolysate by three-day cultivation with cells showed evidence for stimulation of the expression of T-lymphocytes (CD3+) and their subpopulation with helper activity (CD4+).