Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:6.3.5.5 (CPS)
 1,262 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Anti-CRP and complement treatment of human peripheral blood lymphocytes significantly reduces natural killer (NK) cell-mediated cytotoxicity to K562 target cells as well as to MOLT-4 target cells. Although not all activity is eliminated by treatment of effector cells with antibody and complement, the reduction of NK function indicates that C-reactive protein (CRP) is present on a significant proportion of NK cells. Higher concentrations of anti-CRP or anti-CRP F(ab')2 fragments also reduce NK function; this suggests that CRP is not only present on these effector cells but may also play a role in NK-mediated killing. We initially suspected that CRP-ligand interactions might be involved in effector-target cell recognition. Several lines of evidence suggest that this is not the case. While F(ab')2 anti-CRP will block NK function, Fab anti-CRP will not, suggesting that the NK response is not impaired when surface CRP (S-CRP) is blocked but is only inhibited when the S-CRP is cross-linked and modulated. Neither CRP-C polysaccharide complexes (CRP-CPS) nor concentrations of CPS ranging from 0.1 microgram/ml to 200 micrograms/ml have any effect on NK cell-mediated killing. Treatment of target cells with a ligand for CRP or CRP prior to co-culture with NK effectors does not augment NK function. Single cell assays clearly demonstrate that high concentrations of anti-CRP have no effect on the formation of effector-target cell conjugates. Although these concentrations of anti-CRP do not block effector-target cell conjugation in the single cell assay, they do block the killing of conjugated target cells. In total, this evidence strongly suggests that although CRP appears to be involved in NK-mediated killing, it is not involved in effector-target cell-mediated recognition.
 ...
PMID:C-reactive protein is involved in natural killer cell-mediated lysis but does not mediate effector-target cell recognition. 358 16

We reported previously that C-reactive protein (CRP), when complexed to a multivalent binding specificity, can bind to a subset of lymphocytes that bear the IgG Fc receptor. Recently we showed that anti-CRP plus complement depletes natural killer function. We now show the detection of CRP on the surface (S-CRP) of a small percentage of PBL and on a minor population of phagocytic mononuclear cells. S-CRP is not detectable by direct immunofluorescence, but is readily discernible by using more sensitive techniques such as biotinylated anti-CRP with fluorescent avidin or indirect immunofluorescence with monoclonal anti-CRP. S-CRP is expressed in the absence of calcium, whereas the binding of complexed CRP is calcium dependent. S-CRP does not appear to be the exclusive binding site for CRP-CPS because anti-CRP does not block the binding of complexed CRP. Both the binding site for complexed CRP and S-CRP can be capped off; however, the kinetics of capping of these two surface molecules is different. Cells binding complexed CRP are OKT11-, whereas a significant number of PBL bearing S-CRP are OKT11+. Therefore cells bearing S-CRP appear to be a separate population from those that bind complexed CRP. These studies establish the presence of S-CRP on a subpopulation of lymphocytes, define conditions required for its detection, and speak to certain of the relationships between S-CRP and the binding site of CRP-CPS complexes.
 ...
PMID:C-reactive protein antigenicity on the surface of human lymphocytes. 635 57

Functional NK activity can be removed from human PBL and from phagocyte- and T cell-depleted LGL preparations by treatment with antisera specific for C-reactive protein (CRP) in the presence of complement (C). Pretreatment of NK effector cells with high concentrations of anti-CRP in the absence of C also depletes functional activity. These results indicate that CRP or an antigenically similar molecule is present on a population of NK effector cells. Fluorescent antibody studies in which biotin-avidin amplification was used confirm the presence of surface CRP (S-CRP) on a small percentage of nonphagocytic peripheral blood mononuclear cells. S-CRP readily caps off, which suggest that removal by capping obviates killing by this cell population. This indicates that S-CRP or a molecule that co-caps with S-CRP may be required for successful effector-target cell interaction. The addition of exogenous CRP or CRP-CPS complexes, however, does not alter NK responses. A subpopulation of lymphoid cells responsible for functional NK activity therefore appears to bear surface CRP.
 ...
PMID:Possible role for C-reactive protein in the human natural killer cell response. 684 19

We previously reported that C-reactive protein (CRP), an acute phase reactant, inhibits platelet activation through an effect upon a factor(s) critical to ADP-mediated secondary wave platelet aggregation but independent of a direct effect upon platelet contractile elements. However, a role for an accessory factor in this inhibitory effect became of concern because of an inconsistency in the effects of CRP preparations upon the platelet: inhibition was lost upon storage and CRP preparations differed, on a weight basis, in inhibitory capacity and sensitivity to the presence of the CRP ligand C-polysaccharide (CPS(. The studies presented herein were thus intended to assess whether an accessory factor was involved in the inhibition of platelet activation observed with CRP. We report that the activity of the inhibitory CRP preparations resulted from association with a low molecular weight factor (LMF) with an apparent nominal molecular weight of 8300-12,500 and an A280:A260 ratio of approximately 0.4. Purified CRP did not inhibit platelet responsiveness but CRP with associated LMF (CRP-LMF) did. Moreover, the inhibitory capacity of CRP-LMF but not LMF was substantially reversed in the presence of CPS. These studies indicate that the platelet inhibitory properties of CRP preparations result from and are contingent upon the presence of a co-isolating low molecular weight factor.
 ...
PMID:Platelet inhibitory effects of CRP preparations are due to a co-isolating low molecular weight factor. 705 62

C-reactive protein (RP) and serum amyloid P component (SAP) have been identified for the first time in rat serum and isolated by calcium-dependent affinity chromatography. Rat CRP closely resembled human CRP in its amino acid composition, in having five subunits per molecule and in its electron microscopic appearance as a pentameric annular disc. It differed, however, from all other mammalian CRP's characterised hitherto in being a glycoprotein bearing a single complex oligosaccharide on each polypeptide subunit. Furthermore one pair of tis subunits per molecule was linked by a interchain disulphide bridges whereas in other animals the subunits of both CRP and SAP are all non-covalently associated. The serum concentration of CRP in normal healthy laboratory rats and in specific pathogen-free rats was 300-600 micrograms/ml which is much greater than has been described in any other species and exceeds even maximal acute phase levels of CRP in man. Following injections of casein or croton oil, serum CRP levels rose to a maximum of about 900 micrograms/ml. Rat CRP bound to pneumococcal C-polysaccharide (CPS( but, in marked contrast to the behaviour of CRP from man, rabbit and marine teleost fish, it did not precipitate with CPS solutions, agglutinate CPS-coated sheep erythrocytes or initiate complement activation. Rat SAP, like SAP of other species, was a glycoprotein but unlike them it was composed only of a single pentameric disc not two such discs interacting face-to-face. The normal level of SAP in rat serum was 20-50 micrograms/ml, very similar to the levels seen in man, and it did not behave as an acute phase reactant in response to casein or croton-oil injections. In this respect it resembled human SAP but differed from murine SAP which is a major acute phase reactant.
 ...
PMID:Isolation and characterization of C-reactive protein and serum amyloid P component in the rat. 705 68

The functional similarities between C-reactive protein (CRP) and immunoglobulin raised the possibility that modified CRP might resemble immunoglobulin in its activating effects upon the human platelet. Thermally-aggregated CRP (H-CRP), but not unmodified CRP, induced reactions of aggregation and secretion from isolated platelets; maximum responses occurred with less than 50 microgram/ml H-CRP and were similar to responses mediated by thermally-aggregated human IgG (AHGG). Platelet activation induced by H-CRP was sensitive to the presence of EDTA and dibucaine, required metabolic energy and was inhibited by increased levels of cAMP. Like AHGG, H-CRP acted synergistically with other platelet stimulators, although on a weight basis H-CRP appeared approximately ten- to twenty-fold more effective than AHGG. Complexes formed between CRP and certain of its polycationic ligands (PLL and protamine) shared platelet activating properties with H-CRP, whereas complexes of CRP and CPS did not. These data point to the ability of appropriately modified CRP to stimulate or enhance platelet responsiveness, and taken together with those reactivities described previously between modified CRP and certain lymphocytes, phagocytes, and the complement system, support the concept that CRP can initiate biological activities similar to those mediated by immunoglobulin.
 ...
PMID:Activation of platelets by modified C-reactive protein. 706 Nov 5