Human serum mannose-binding lectin (MBL)-associated serine protease-1 (MASP-1): determination of levels in body fluids and identification of two forms in serum.
We developed an ELISA for human serum MASP-1, a C1s-like serine protease which is known to function in C4 and C2 activation. We then determined MASP-1 levels in 1063 sera from normal Japanese subjects ranging in age from 3 to 100 years, as well as in certain body fluids using this assay. Individual serum MASP-1 levels ranged from 1.48 to 12.83 microg/ml, with a normal frequency distribution pattern. The arithmetic mean +/- s.d. of MASP-1 levels in serum was 6.27 +/- 1.85 microg/ml, whereas levels of MASP-1 in cerebrospinal fluid and in urine were almost undetectable. When the mean +/- s.d. of serum MASP-1 was calculated for each age group (10 year range) and values were then compared, the age group consisting of 3-9-year-olds (7.54 +/- 1.39 microg/ml) was found to have the highest value. When MASP-1 was measured in cord blood, it was shown that levels were already as high as those of 3-9-year-olds. The serum MASP-1 level was found to be as strongly dependent on age as is the serum MBL level. MASP-1 and MBL are thought to play an active part in immunity in younger people. It was found that the serum level of MASP-1 was much higher than that of MBL, and the major portion of human serum MASP-1 appeared to exist in the circulation as a form unbound to MBL.
Terai
I
I
Division of Clinical Pathology, Hokkaido Institute of Public Health, Sapporo, Japan.
Kobayashi
K
K
Matsushita
M
M
Fujita
T
T
D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000097:blood; D001826:Body Fluids / Q000201:enzymology; D002648:Child; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D050606:Mannose-Binding Protein-Associated Serine Proteases; D008875:Middle Aged; D012697:Serine Endopeptidases / Q000097:blood*
C105296:MASP2 protein, human; D050606:Mannose-Binding Protein-Associated Serine Proteases; D012697:Serine Endopeptidases