Serum content of the C-propeptide of the cartilage molecule type II collagen in children.
OBJECTIVE
The C-propeptide of cartilage type II procollagen, together with the N-propeptide, are removed from newly synthesized procollagen during collagen fibril assembly in cartilage matrix. The presence and content of the C-propeptide reflect the synthesis of this molecule. Recently, we showed that serum levels of the C-propeptide are increased in adults with rheumatoid arthritis, pointing to increased synthesis of this molecule. In this study we examined its content in the sera of children to determine whether it changes during development.


METHODS
Sera were obtained from 44 premature infants (cord blood), 75 children (0-18 years), 14 young adults (18-22 years) and 47 adults (35-60 years). The concentration of serum C-propeptide of type II procollagen was determined by a solution phase competitive inhibition radioimmunoassay which uses a polyclonal antiserum specific for the bovine and human C-propeptide.


RESULTS
Compared with adults, concentrations of the C-propeptide of type II procollagen were significantly elevated in children of ages 0-14 years. Concentrations were constant until 10 years of age (premature infants: 14.5 +/- 1.4 ng/ml, mean +/- SE; 0-10 years: 13.6 +/- 1 ng/ml). In children of ages 10-14 years, during which the pubertal growth spurt is ordinarily observed, the mean concentration increased (10-14 years: 21.6 +/- 0.7 ng/ml) although not significantly due to the variation between individuals. Concentrations at all ages younger than 14 were significantly greater than those in older adolescents ages 14-18 (6.3 +/- 0.7 ng/ml), young adults (8.4 +/- 2.0 ng/ml) and adults (5.7 +/- 0.4 ng/ml). Serum concentrations did not show significant differences with respect to sex, but varied from child to child at any given age.


CONCLUSIONS
The measurement of this circulating C-propeptide may be of use in studying the biochemical and physiological bases of changes in cartilage turnover in children, and abnormalities thereof.
Carey
D E
DE
Shriners Hospital for Crippled Children, Department of Surgery, McGill University, Montreal, Canada.
Alini
M
M
Ionescu
M
M
Hyams
J S
JS
Rowe
J C
JC
Rosenberg
L C
LC
Poole
A R
AR
D000293:Adolescent; D000328:Adult; D002135:Calcium-Binding Proteins / Q000097:blood*; D002356:Cartilage / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D003094:Collagen / Q000097:blood*; D024043:Collagen Type II; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D009994:Osmolar Concentration; D011863:Radioimmunoassay
D002135:Calcium-Binding Proteins; D024043:Collagen Type II; C040072:chondrocalcin; D003094:Collagen