Generation of anti-insulin-like growth factor-binding protein-related protein 1 (IGFBP-rP1/MAC25) monoclonal antibodies and immunoassay: quantification of IGFBP-rP1 in human serum and distribution in human fluids and tissues.
The IGF-binding protein (IGFBP)-related proteins (rPs) are a group of recently described cysteine-rich proteins that share significant amino-terminal structural similarity with the conventional IGFBPs. IGFBP-rP1 (also known as MAC25/angiomodulin/prostacyclin-stimulating factor and T1A12), regulates cellular proliferation, adhesion, and angiogenesis and stimulates prostacyclin synthesis. We characterized new monoclonal antibodies generated against IGFBP-rP1 and have used them to study the distribution of IGFBP-rP1 in human biological fluids and tissues. Additionally, we have developed a noncompetitive sandwich-type immunoassay to quantitate the concentrations of IGFBP-rP1 in human serum. IGFBP-rP1 was readily detectable in serum, urine, amniotic fluid, and cerebrospinal fluid by immunoblot analysis. Evaluation of the newly developed immunoassay demonstrated acceptable analytical performance, with a detection limit of 0.7 micro g/liter, a dynamic range of 3.1-100 micro g/liter, and intra- and interassay coefficients of variation of 2.5-6.8% and 3.1-6.4% at approximately 24-85 ng/ml IGFBP-rP-1, respectively. No significant cross-reactivity with IGFBP-1-6 was observed. In random normal human adult sera (n = 37), the median IGFBP-rP1 was 21.0 micro g/liter, and values did not correlate with levels of IGF-I (r = 0.085, P = 0.61), IGF-II (r = 0.051, P = 0.75), or IGFBP-3 (r = 0.061, P = 0.74). The monoclonal anti-IGFBP-rP1 antibodies also readily detected IGFBP-rP1 expression in human tissue sections, with preferential expression of IGFBP-rP1 in the microvascular endothelium associated with tumorigenesis. In summary, using newly developed IGFBP-rP1 monoclonal antibodies, we confirm the presence of IGFBP-rP1 in the major human body fluids, provide quantitative normative data on the concentrations of IGFBP-rP1 in human serum, and show preferential expression of IGFBP-rP1 in the microvascular endothelium associated with tumorigenesis. The use of these novel IGFBP-rP1 detection tools should prove useful in the elucidation of the biological role(s) of this protein.
López-Bermejo
Abel
A
Department of Pediatrics, Oregon Health Sciences University, Portland, Oregon 97201, USA.
Khosravi
Javad
J
Corless
Christopher L
CL
Krishna
Radha G
RG
Diamandi
Anastasia
A
Bodani
Umesh
U
Kofoed
Eric M
EM
Graham
Donna L
DL
Hwa
Vivian
V
Rosenfeld
Ron G
RG
D000328:Adult; D000368:Aged; D000818:Animals; D000911:Antibodies, Monoclonal / Q000096:biosynthesis / Q000276:immunology*; D000918:Antibody Specificity; D001826:Body Fluids / Q000737:chemistry; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005260:Female; D006801:Humans; D006825:Hybridomas; D018970:Insulin-Like Growth Factor Binding Protein 1 / Q000032:analysis* / Q000097:blood / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008875:Middle Aged; D011247:Pregnancy
D000911:Antibodies, Monoclonal; D018970:Insulin-Like Growth Factor Binding Protein 1