title: Analysis of cell-free human alpha1 integrin with a monoclonal antibody to the I-domain: detection in ocular fluid and function as an adhesion substrate.
abstract: The alpha1 beta1 integrin, an inserted (1) domain containing collagen receptor, is expressed in the cell surface membrane of normal and malignant cells, and may play a role in their migration through tissues or in metastatic spread. Here we report that a functional anti-human alpha1beta1 integrin monoclonal antibody (mAb) (1B3.1) directly and specifically binds plastic bound recombinant human alpha1 I-domain protein containing the collagen binding site. Detection was diminished by acidification of the I-domain protein but was enhanced by increasing concentrations of Mg2+ cation. Furthermore, we detected binding of the mAb to proteins from the ocular fluids of 6 patients, with the highest concentration, corresponding to 22.1 ng/ml of I-domain, found in a sample from the eye of a patient with metastatic lung adenocarcinoma. Interestingly, we found that both SKNSH neuroblastoma cells and virally transformed human T cells adhered specifically to plastic wells coated with either immobilized collagen IV or alpha1 I-domain. MAb I B3.1 inhibited adhesion to collagen IV but not to immobilized I-domain. These results suggest a novel function for cell free alpha1 I-domain as a substrate for cellular adhesion, which may have relevance in tumor spread in vivo.
authors.affiliation: Department of Medicine, Chaim Sheba Medical Center, Tel Hashomer, Israel. ibank@post.tau.ac.il
authors.forename: I
authors.initials: I
authors.lastname: Bank
authors.forename: J
authors.initials: J
authors.lastname: Kapyla
authors.forename: A
authors.initials: A
authors.lastname: Grinbaum
authors.forename: R
authors.initials: R
authors.lastname: Doolman
authors.forename: J
authors.initials: J
authors.lastname: Bank
authors.forename: B A
authors.initials: BA
authors.lastname: Sela
mesh_terms: D000230:Adenocarcinoma / Q000175:diagnosis / Q000556:secondary; D000911:Antibodies, Monoclonal / Q000276:immunology*; D001082:Aqueous Humor / Q000737:chemistry*; D002386:Cataract / Q000175:diagnosis; D002412:Cations / Q000737:chemistry; D015815:Cell Adhesion Molecules / Q000276:immunology*; D002474:Cell-Free System; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods*; D005134:Eye Neoplasms / Q000556:secondary; D006801:Humans; D039423:Integrin alpha1 / Q000737:chemistry / Q000276:immunology* / Q000502:physiology; D039222:Integrin alpha1beta1 / Q000276:immunology; D008175:Lung Neoplasms / Q000175:diagnosis / Q000473:pathology; D017434:Protein Structure, Tertiary
chemical_list: D000911:Antibodies, Monoclonal; D002412:Cations; D015815:Cell Adhesion Molecules; D039423:Integrin alpha1; D039222:Integrin alpha1beta1