Single administration of enterococcal preparation (FK-23) augments non-specific immune responses in healthy dogs

Influence of a single administration of heat-killed Enterococcus faecalis FK-23 preparation (FK-23) on non-specific immune responses was evaluated in healthy dogs. The dogs received a single administration of FK-23 at a dose of 100 mg/kg perorally and thereafter a complete blood count (CBC), leukocyte differential count, phagocytic activity of peripheral blood neutrophils and a lymphocyte blast transformation (LBT) test were assessed. Although FK-23 had no effect on the CBC or leukocyte differential count, treatment of the drug caused a 1.4-fold increase in neutrophil phagocytosis compared to FK-23 non-treated healthy dogs. LBT activities of phytohemagglutinin (PHA) and pokeweed mitogen (PWM) were also activated to twice the control levels and that of concanavalin A (Con A) was increased to one and a half times by the FK-23 treatment. Thus, a single administration of FK-23 appears to augment host resistance through stimulation of the non-specific immune responses in vivo.