Endogenous antibodies to bovine lactoperoxidase in children and adolescents

Sera from 146 children and adolescents (70 girls and 76 boys, median age 6 years; range 8 months - 18 years) were analysed for the presence of antibodies to bovine lactoperoxidase (LPO) using a solid-phase immunosorbent radioassay. LPO antibodies were present in all but one serum. The antibody titres varied from 1/5 to greater than 1/5000 (final dilutions). Most of the individuals had antibody titres between 1/50 to 1/5000. Because of the frequent occurrence of LPO antibodies in human beings, the presence of LPO antibodies in the serum must be regarded as a physiological phenomenon.