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At least 91 records · Page 5Linked to original sources
PubMed2002

Use of enzyme treatment to enhance reactivity of HLA and platelet-specific antibodies in solid-phase RBC adherence assays.

BACKGROUND: Solid-phase RBC adherence (SPRCA) assays (Immucor) detect HLA and/or platelet-specific antibodies. Pretreatment of reagent platelets with enzymes was investigated to determine whether the sensitivity of the assay could be increased. STUDY DESIGN AND METHODS: SPRCA testing, following the manufacturer's directions, was performed on 51 sera from patients with either a positive SPRCA antibody screen, suboptimal clinical responses to platelet transfusions, and/or suspected immune thrombocytopenic purpura; testing was also performed following pretreatment of the reagent platelets with bromelin, papain, or ficin. Sera from 23 patients having negative routine SPRCA antibody screens and good clinical responses to transfusion were tested as controls. Lymphocytotoxic antibody testing was also performed on selected samples. The effectiveness of enzyme treatment was judged by the increase in the proportion of reagent platelets reacting with the sample and the observed reaction strengths. RESULTS: Pretreatments of reagent platelets with all three enzymes increased the reactivity of known antibodies and detected some HLA and platelet-specific antibodies that had not reacted in routine testing. The clinical significance of the antibody specificities detected only after enzyme pretreatment was verified by a correlation with results from transfusing antigen-negative units. Only occasional false-positive results after enzyme pretreatment were observed. CONCLUSIONS: The use of enzyme pretreatment of SPRCA screening strips can provide information that is useful in selecting appropriate units for transfusion.

Antibody Specificity↗
PubMedDate not supplied

Rapid testing of ficinized cells in capillary tubes.

A technique is described for capillary tube testing using small amounts with cell rapidly treated with a 4% ficin solution. This test aids antibody identification and cell screening.

Capillary Action↗
PubMedDate not supplied

Concomitant T- and Tk-activation associated with acquired-B antigens.

Three patients with acquired-B antigens are reported whose red blood cells also manifested T- and Tk-activation. The results of tests using purified Arachis hypogaea and Bandeiraea simplicifolia (BS II) lectins, and red blood cells either T, Tk or both T and Tk-activated by bacterial enzymes in vitro, suggest that the acquired-B phenomenon, T-activation and Tk-activation result from the action of different bacterial enzymes.

ABO Blood-Group System↗
PubMedDate not supplied

A strong antibody reacting with enzyme modified E positive red blood cells.

A high titer antibody was discovered in a healthy young man of blood group A1 R2r. The antibody strongly agglutinated all E positive red blood cells including his own, which had been modified by papain, ficin and bromelin, but only very weakly when modified by trypsin. The antibody was shown to be an IgM antibody. It did not react with unmodified red blood cells.

Adult↗
PubMedDate not supplied

Polyagglutination due to combined T and Tk activation.

The development of polyagglutination in vivo in two patients with an unusual presentation of features of both T and Tk activation is described. The problems of laboratory diagnosis of these red blood cell anomalies and the impact of these anomalies in clinical management is discussed.

Absorption↗
PubMedDate not supplied

A serum factor which inhibits serologic reactions with enzyme-treated red blood cells.

Two patients' sera inhibited agglutination of enzyme-treated red blood cells by antibodies. This blocking effect was detected by using a mixture of antibodies as an enzyme test reagent for the routine control of a two-stage papain test. The blocking factor appeared to be IgG and its effect was complement dependent. It blocked reactions with red blood cells treated with papain, bromelin, or ficin. Reactions with both IgM and IgG antibodies of various specificities were blocked. The presence of the blocking factor in a patient's serum may result in failure to detect clinically significant antibodies unless a control system is used which will confirm that the cells in each test can be agglutinated by enzyme reacting antibodies.

Aged↗
PubMedDate not supplied

An antibody that recognizes a determinant common to S and s-bearing sialoglycoproteins.

We describe an antibody, made by an individual of the phenotype M+, N+, S+, s+, U+, that reacted only with ficin or papain-treated red blood cells, and that initially appeared to have anti-S specificity. However, further studies revealed that the antibody, which did not have anti-U specificity, recognized a determinant present on S+, s-, U+, and S-, s+, U+, but missing from S-, s-, U-, and S-, s-, U+, red blood cells. The specificity of this antibody is discussed in terms of current knowledge of the structure of the Ss sialoglycoprotein.

Aged↗
PubMedDate not supplied

A case of polyagglutination with features of Th and Tk activation associated with an acquired B antigen.

A case is reported of polyagglutination with features of both Tk and Th activation associated with an acquired B antigen. Reactions with polybrene, Glycine soja, and Bandeiraea simplicifolia II indicated the presence of Tk activation. However, the reactivity of the patient's erythrocytes with Arachis hypogoea was greatly reduced by treatment with ficin, indicating the concomitant presence of Th activation.

ABO Blood-Group System↗
PubMedDate not supplied

Serologic and IgG subclass characterization of Cartwright (Yt) and Gerbich (Ge) antibodies.

Examples of anti-Yta and anti-Ge were tested for reactivity with red cells treated with proteolytic enzymes and with antisera of known IgG specificity. Eight of 14 examples of anti-Yta did not react as well with cells treated with either papain or ficin; treatment with trypsin did not reduce reactivity. Four examples of the anti-Yta were IgG4; the others tested did not react with IgG subclass antisera. Of 13 examples of anti-Ge, seven failed to react with red cells treated with trypsin, ficin, or papain. Nine examples were IgG1, one was IgG1 plus IgG3, and three did not react with IgG subclass antisera.

Blood Group Antigens↗
PubMed1989

Vancomycin-induced red cell aggregation.

Vancomycin, an antibiotic similar in structure to ristocetin, is used to treat staphylococcal infections. However, vancomycin-induced hemagglutination complicated red cell (RBC) serologic testing in the blood bank. At concentrations greater than 3.0 mg per ml, vancomycin caused spontaneous macroscopic red cell (RBC) aggregation; concentrations of 2.0 and 2.5 mg per ml were associated with weakly positive aggregation with anti-IgG and polyspecific antiglobulin reagents negative with anti-complement; and concentrations less than 1.5 mg per ml had no apparent effect. Ficin-treated RBCs demonstrated negative reactions with the antiglobulin reagents. Vancomycin-induced aggregation was reversed partially with 0.2 M trisodium citrate, and supernatant transfer studies showed that normal RBCs retained a significantly (p less than 0.025) greater percentage of vancomycin than did ficin-treated RBCs. Vancomycin causes the aggregation of RBCs, which can be a source of confusion in the blood bank. The mechanism(s) through which vancomycin enhances aggregation may be related to its polycationic properties and to its direct protein binding to the RBC membrane, although other nonimmunologic mechanisms may be operative.

Citrates↗
PubMed1993

Lack of clinical significance of "enzyme-only" red cell alloantibodies.

In a retrospective study on samples from 10,000 recently transfused patients, 35 samples were found to contain an antibody that reacted with ficin-treated red cells but was not demonstrable by low-ionic-strength saline solution and indirect antiglobulin test (LISS-IAT). In those 35 patients, the specificity of the antibody was such that each patient would have been transfused with antigen-negative blood had the antibody reacted in LISS-IAT. Tests on red cells from the units already transfused showed that 19 patients had among them received, by chance, 32 antigen-positive and 74 antigen-negative units. The remaining 16 patients had among them received 57 units that were, again by chance, all antigen negative. One patient given antigen-positive blood suffered a delayed transfusion reaction; in two others the antibodies became LISS-IAT active after transfusion. However, similar changes to the LISS-IAT-active state were seen with two antibodies of patients given only antigen-negative blood. Also found in the 10,000 patients were 28 clinically insignificant antibodies, 77 sera in which the antibody was too weak to identify, and 216 autoantibodies that reacted only with ficin-treated red cells. These data support a belief, generally held in the United States but not necessarily elsewhere, that the use of protease-treated red cells for routine pretransfusion tests creates far more work than the accrued benefits justify.

Clinical Enzyme Tests↗
PubMed1998

Various forms of rabbit plasma alpha-1-antiproteinase.

Amino acid sequencing of the ficin-derived C-terminal fragments of alpha-1-antiproteinase (also called alpha-1-antitrypsin or alpha-1-proteinase inhibitor) prepared from rabbit plasma revealed the presence of the E isoform, which had been confirmed in the cDNA library in addition to the F and S-1 forms. The S-2 form was identified in inflamed rabbit plasma. The ficin digest of human plasma alpha-1-antitrypsin resulted in a major fragment of the M type. Multiple forms of alpha-1-antiproteinase in the rabbit plasma implicate the unknown functions other than the inhibition of neutrophil elastase.

Amino Acid Sequence↗
PubMed2003

Absence of protein G-Fc interaction in ficin-derived mouse IgG1 digests.

Typical procedure for IgG fragmentation is based on proteolytic cleavage at the hinge region and usually involves a post-digestion purification step. In mice, IgG1 has been found to bind poorly to protein A. As a result, protein G chromatography could be considered as an alternative for Fc removal. Protein G is generally expected to bind specifically to the Fc region of IgG, but applying protein G for the purification of Fab2 fragment of mouse monoclonal IgG1 under standard physiological conditions, we obtained reproducible clone-independent negligible protein G-Fc reactivity and strong protein G-Fab2 interaction.

Animals↗
PubMed1988

The use of proteolysis with ficin, for immunostaining of paraffin sections. A study of lymphoid, mesenchymal, and epithelial determinants in human tissues.

In order to maximize staining, modifications of immunostaining methods have included proteolytic enzyme digestion of tissue. The authors performed a study of the effect of ficin in 110 paraffinized specimens, including tonsil, lymph nodes, benign vascular and nerve sheath tumors, and various carcinomas and sarcomas. This agent was compared with pepsin and bromelain, as alternative proteases. A panel of monoclonal and polyclonal antibodies was used, with and without previous digestion by ficin, pepsin, and bromelain. A score was assigned to each stain, based on the number and intensity of reactive cells. Ficin enhanced staining markedly in immunostains with antibodies to keratin and Factor VIII-related antigen (F8RAG). Conversely, it abolished staining for LN-2 (a lymphoid marker) and weakened reactivity for S-100 in nerve sheath tumors. Bromelain produced similar results, except that it enhanced S-100. Pepsin was comparatively less active than ficin and bromelain overall but did produce the greatest amplification of vimentin staining in sarcomas. Digestion with any of the three enzymes failed to influence reactivities of leukocyte common antigen, UCHL-1 (a lymphoid marker), alpha-1-antichymotrypsin, carcinoembryonic antigen, epithelial membrane antigen, and blood group isoantigens. These results may reflect a dissimilar recognition of peptide targets in some antigenic proteins, by ficin, bromelain, and pepsin. Hence, one enzymatic agent is unlikely to produce optimal staining for all determinants. With this proviso, however, ficin appeared to be the best general enhancer for antigens known to require vigorous digestion (e.g., keratin; F8RAG) for optimal reactivity in paraffin sections.

Cysteine Endopeptidases↗
PubMed1987

Enhancement of testicular cysteine proteinase inhibitor level in vitamin E-deficient rats.

The effect of vitamin E deficiency on levels of proteinase inhibitors in sex glands of male rats was studied. Inhibitor levels against cysteine proteinases, such as ficin and cathepsin H, and against serine proteinase such as trypsin were examined. Vitamin E deficiency for 4 mo after weaning induced a fivefold increase in cysteine proteinase inhibitor level in testis, a two- to fourfold increase in prostate and epididymis and no change in seminal vesicle. No appreciable change was observed in trypsin inhibitor level in testis, epididymis or seminal vesicle. Therefore, vitamin E deficiency was reflected most sensitively by the cysteine proteinase inhibitor level in testis. These observations agree with our previous findings that alpha-cysteine proteinase inhibitors in serum increased greatly whereas trypsin inhibitor in serum did not change in vitamin E-deficient rats. Major histological changes were observed in the testes of rats fed a vitamin E-deficient diet for 4 mo, although testis weight was not significantly affected by vitamin E deficiency.

Animals↗
PubMed1987

Comparative study on the active sites of ficin and papain by the spin labeling method.

Ficin was alkylated with a series of haloacetamide spin labels with various distances between the spin probes and reactive groups. From the relation of these distances to the tau c values of the labels incorporated into protein, it was estimated that the depth of the active site hole of ficin is ca. 8 A. The results are somewhat different from those reported previously for papain (S. Nakayama et al. (1981) Biochem. Biophys. Res. Commun. 98, 471-475). Examination of the pH dependence of the ESR spectra for ficin and papain alkylated with an iodoacetamide or a maleimide spin label suggested that these enzymes have an amino acid residue of pKa 4 (probably a histidine residue) around the active site cysteine and that the active site conformations change at around pH 5.

Binding Sites↗