POLYSIALYLATED NEURAL CELL-ADHESION MOLECULE SERUM LEVELS IN NORMAL-CHILDREN

Serum concentrations of polysialylated neural cell adhesion molecule ( PSA-NCAM), a developmentally regulated form of the NCAM, have been rec ently described to be elevated in children with rhabdomyosarcoma and n euroblastoma, proving PSA-NCAM to be a tumor marker of diagnostic rele vance to these malignancies. The present investigation was undertaken to define age-dependent reference intervals in normal children. Serum concentrations of polysialylated NCAM were determined in 366 children aged newborn to 17 y and in 18 adult patients by an immunoluminescence assay using the polysialic acid-specific MAb 735. Serum levels in new born children were 51.7 kU/L (mean +/- 12.0 kU/L SD), whereas in adult patients they were 9.9 kU/L (mean +/- 3.5 kU/l SD). Assigning the pat ients to 14 different age groups, a gradual decay of PSA-NCAM serum co ncentrations was observed, and therefore, mean levels and empirical in terpolated percentiles were determined for every age group. Applying s pecially fitted logistic functions, two different sigmoid graphs were obtained describing the age-dependent decrease of serum PSA-NCAM durin g the neonatal period and during childhood. The age at which the level s reach half the initial value was located at 3.1 d (mean +/- 2 d SE) and 14 y (mean +/- 1 y SE), respectively. There was no difference betw een male and female individuals. Repeated measurements revealed variat ions below 10%. For the first time, our study describes serum levels o f PSA-NCAM in children of different age and their gradual decay until adulthood.