Natural antibodies in mammalian sera to folinic acid and methotrexate

Borsos, Tibor; Chapuis, Rose Marie; Langone, John J.

doi:10.1016/0161-5890(81)90007-9

Cited by 12 publications

(2 citation statements)

References 13 publications

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“…Protein A selectively binds IgG, and Con A binds IgM. By using a procedure identical with that described by Borsos et al (1981), plasma Ma was preabsorbed with Protein A-Sepharose, and the DNA-binding activity was abolished, whereas plasma Ma preabsorbed with Con A-Sepharose retained more than 90% of its DNA-binding capacity.…”

Section: Methodsmentioning

confidence: 99%

Complement-component-C3-opsonized immunoglobulin G anti-DNA antibodies do not bind effectively to red blood cells unless aggregated on a high-Mr DNA matrix

Horgan¹,

Taylor²

1984

Biochemical Journal

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Large, soluble ds (double-stranded) DNA-IgG (immunoglobulin G) anti-dsDNA immune complexes (greater than or equal to 200 S) that were previously opsonized with complement were digested with DNAase. The small complement-component-C3-fragment-labelled IgG (11-14 S) that was then isolated did not bind effectively to complement receptor type 1 on human red blood cells. However, when this IgG was immune-complexed with 3H-labelled PM2 (bacteriophage directed against a marine Pseudomonas) dsDNA (Mr approximately 6 X 10(6), substantial binding of both the DNA antigen and IgG to the erythrocytes was demonstrable.

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Section: Methodsmentioning

confidence: 99%

Complement-component-C3-opsonized immunoglobulin G anti-DNA antibodies do not bind effectively to red blood cells unless aggregated on a high-Mr DNA matrix

Horgan¹,

Taylor²

1984

Biochemical Journal

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“…In this system, an alternative mechanism of autocatalytic activation is adapted for the activation of the first protease in the cascade, C1r, which, in turn, triggers a proteolytic activation cascade, leading to the formation of the complement complex (21). The autoactivation of the C1r protease can be induced by the binding of C1 complex to an antibody-antigen complex (22), which serves a nonprotease function to induce the activation of the first protease in the complement system. For most serine protease cascades, however, little is known about the nature of the signal initiating the cascade.…”

Section: S1p May Function As a Nonprotease Initiator For A Possible Smentioning

confidence: 99%

Sphingosine 1-Phosphate, Present in Serum-derived Lipoproteins, Activates Matriptase

Benaud¹,

Oberst²,

Hobson³

et al. 2002

Journal of Biological Chemistry

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We describe here a novel biological function of sphingosine 1-phosphate (S1P): the activation of a serine protease, matriptase. Matriptase is a type II integral membrane serine protease, expressed on the surface of a variety of epithelial cells; it may play an important role in tissue remodeling. We have previously reported that the activation of matriptase is regulated by serum. We have now identified the bioactive component from serum. First, the activity was observed to co-purify with lipoproteins by conventional liquid chromatography and immunoaffinity chromatography. The ability of lipoproteins to induce the activation of matriptase was further confirmed with commercial preparations of low density lipoprotein (LDL) and very low density lipoprotein (VLDL). Next, we observed that the bioactive component of LDL is associated with the phospholipid components of LDL. Fractionation of lipid components of LDL by thin layer chromatography (TLC) revealed that the bioactive component of LDL comigrates with S1P. Nanomolar concentrations of commercially obtained S1P were then observed to induce the rapid activation of matriptase on the surfaces of nontransformed human mammary epithelial cells. Other structurally related sphingolipids, including dihydro-S1P, ceramide 1-phosphates, and sphingosine phosphocholine as well as lysophosphatidic acid, can also induce the activation of matriptase, but at significantly higher concentrations than S1P. Furthermore, S1P-dependent matriptase activation is dependent on Ca 2؉ but not via G i protein-coupled receptors. Our results demonstrate that bioactive phospholipids can function as nonprotein activators of a cell surface protease, suggesting a possible mechanistic link between S1P and normal and possibly pathologic tissue remodeling.Physiologic and pathologic tissue remodeling involve an interplay of processes involving proteases and growth factors. Whereas growth factors induce cell proliferation and motility and function as chemoattractants, proteases directly promote cell migration by degrading the surrounding extracellular matrix barrier. However, the participation of proteases in physiologic and pathologic tissue remodeling is more complex, since proteolytic cleavage also serves to expose cryptic sites of extracellular matrix molecules, to activate latent growth factors, and to activate other protease cascades (1, 2). This complexity is exemplified by the epithelium-derived serine protease, matriptase (3, 4) (also known as membrane type serine protease-1 (5) or as epithin, its mouse homologue (6)). Matriptase has been demonstrated to activate the extracellular matrixdegrading protease, urokinase-type plasminogen activator, the potent, motility-inducing hepatocyte growth factor/scatter factor, and the calcium-regulating protease-activated receptor-2 (7, 8). Therefore, matriptase may play an important role in tissue remodeling (7).In addition to its catalytic serine protease domain, matriptase contains a transmembrane domain and two putative regulatory domains: two tandem repea...

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Applications of immobilized protein A in immunochemical techniques

Langone

1982

Journal of Immunological Methods

182

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Natural antibodies in mammalian sera to folinic acid and methotrexate

Cited by 12 publications

References 13 publications

Complement-component-C3-opsonized immunoglobulin G anti-DNA antibodies do not bind effectively to red blood cells unless aggregated on a high-Mr DNA matrix

Complement-component-C3-opsonized immunoglobulin G anti-DNA antibodies do not bind effectively to red blood cells unless aggregated on a high-Mr DNA matrix

Sphingosine 1-Phosphate, Present in Serum-derived Lipoproteins, Activates Matriptase

Applications of immobilized protein A in immunochemical techniques

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