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J A McIntyre

Publications and source records attributed to J A McIntyre.

At least 55 records · Page 3Linked to original sources
PubMed1997

Phospholipid binding plasma proteins required for antiphospholipid antibody detection--an overview.

PROBLEM: Antibodies to phospholipid antigens (aPA) are associated with thrombosis thrombocytopenia and recurrent pregnancy loss. Contemporary data show many aPA target phospholipid-binding plasma proteins and not phospholipids. The purpose of this overview is to describe several phospholipid-binding proteins and provide data to demonstrate how the interaction between phospholipids and phospholipid binding proteins results in expression of neo-autoantigenic epitopes. METHOD: Review of existing data. RESULTS: Illustrations of how certain plasma proteins beta 2 glycoprotein I, prothrombin, high and low molecular weight kininogens interact with the anionic phospholipids cardiolipin and phosphatidylserine and the zwitterionic phospholipid, phosphatidylethanolamine are shown and discussed. A model of aPA mediated thrombosis is presented. CONCLUSIONS: Some aPA recognize phospholipids directly, however, the majority and many which correlate with pathology target phospholipid binding proteins. Published data indicate that aPA represent a constellation of antibodies with multiple specificities. Insight into mechanisms responsible for aPA-associated thrombosis should provide a basis for treatment.

Animals↗
PubMed1997

The reliability of hand-written and computerised records of birth data collected at Baragwanath hospital in Soweto.

This study examined the reliability of hand written and computerised records of birth data collected during the Birth to Ten study at Baragwanath Hospital in Soweto. The reliability of record-keeping in hand-written obstetric and neonatal files was assessed by comparing duplicate records of six different variables abstracted from six different sections in these files. The reliability of computerised record keeping was assessed by comparing the original hand-written record of each variable with records contained in the hospital's computerised database. These data sets displayed similar levels of reliability which suggests that similar errors occurred when data were transcribed from one section of the files to the next, and from these files to the computerised database. In both sets of records reliability was highest for the categorical variable infant sex, and for those continuous variables (such as maternal age and gravidity) recorded with unambiguous units. Reliability was lower for continuous variables that could be recorded with different levels of precision (such as birth weight), those that were occasionally measured more than once, and those that could be measured using more than one measurement technique (such as gestational age). Reducing the number of times records are transcribed, categorising continuous variables, and standardising the techniques used for measuring and recording variables would improve the reliability of both hand-written and computerised data sets.

Data Collection↗
PubMed1996

Autoantibodies to kininogen-phosphatidylethanolamine complexes augment thrombin-induced platelet aggregation.

Autoantibodies to the zwitterionic phospholipid (PL), phosphatidylethanolamine (PE), have been described in patients with thrombotic disease. We have reported that certain anti-PE antibodies (aPE) are not specific for PE, but are directed to PE-binding plasma proteins, high molecular weight kininogen (HK) and low molecular weight kininogen (LK). Kininogens bind to platelets and inhibit thrombin-induced platelet aggregation. This inhibition is specific for thrombin because kininogens do not inhibit platelet aggregation induced by adenosine diphosphate (ADP), collagen or calcium ionophore. To date, a platelet kininogen receptor has not been described. We recently reported that purified kininogens bind to purified PE in vitro. This opens the possibility that kininogens can bind to platelets by virtue of exposed PE in the platelet membrane. We thus questioned if aPE can recognize platelet bound kininogens and negate their antithrombotic property. Our experiments support this possibility by demonstrating that exogenously added kininogen-dependent IgG aPE markedly increased thrombin-induced platelet aggregation in vitro but did not alter ADP-induced aggregation. In contrast, kininogen independent IgG aPE which recognized PE per se did not augment thrombin-induced platelet aggregation. These data support a hypothesis that kininogen dependent aPE may cause thrombosis in vivo due to disruption of the normal antithrombotic effects of kininogen.

Animals↗
PubMed1996

Utilization of intravenous immunoglobulin to ameliorate alloantibodies in a highly sensitized patient with a cardiac assist device awaiting heart transplantation. Fluorescence-activated cell sorter analysis.

Surgery surrounding the use of mechanical assistance in cardiac transplant candidates often leads to multiple blood/platelet transfusions and subsequent development of alloantibodies. This is a case report of a 50-year-old male patient who had received blood transfusions during coronary bypass grafting 9 years earlier. He presented in acute and chronic heart failure and, despite therapy, became moribund with multisystem organ failure. His ejection fraction was 10%. A Novacor ventricular assist device was implanted on May 19, 1995 (day 0). The patient received 44 U of blood and 20 U of platelets. Although his percent reactive antibodies (PRA) were negative before surgery by fluorescence-activated cell sorter analysis, the PRA 3 days after implantation of the ventricular assist device was 80%; it increased to 100% by day 7. In an attempt to decrease the PRA, intravenous immunoglobulin was given at 3-week intervals. The PRA became negative and the patient received a donor heart that was negative by fluorescence-activated cell sorter cross-match on day 64. On days 69-72, a dramatic increase in alloantibody activity was promptly reversed with additional intravenous immunoglobulin. Currently at posttransplant month 12, the patient shows no humoral, cellular, or vascular evidence of rejection.

Blood Transfusion↗
PubMed1996

Detection of IGA anti-OKT3 antibodies in OKT3-treated transplant recipients.

Murine OKT3 monoclonal antibodies function as an immunosuppressant drug for organ transplant recipients. A contraindication to retreatment may develop, however, because a high proportion of OKT3-treated patients form anti-OKT3 antibodies. Previous data have shown that only antiidiotypic IgG antibodies can negate the beneficial effect of the drug. Eighty-two OKT3-treated transplanted patients were tested by ELISA for IgG, IgK and IgA anti-OKT3 antibodies and compared with 200 controls. The anti-OKT3 antibody-positive sera were screened additionally by flow cytometry for the presence of antiidiotypic activity by measuring Ortho OKT3-FITC activity on a CD3-positive cell line, Jurkat, before and after incubation with serial dilutions of patient and control sera. Forty-four of 82 patients developed antibodies to OKT3, 20 manifested IgG, 20 produced both IgG and IgA, and 4 IgA only. We never detected IgM anti-OKT3. Of the 44 anti-OKT3-positive patient sera, 25 showed antiidiotypic specificity. Two IgG/IgA anti-OKT3-positive patient sera were IgG-depleted by Protein G. Both continued to exhibit antiidiotypic IgA activity. IgA anti-OKT3 was associated with low serum OKT3 levels and lack of ability of OKT3 to lower total CD3 cell numbers to therapeutic levels. This is the first report of IgA anti-OKT3 antibody in transplant recipients. Isotype IgA anti-OKT3 was observed in 54% of the patients whose sera tested positive for anti-OM by ELISA. The IgG/ IgA anti-OKT3-positive patient sera tested continued to exhibit antiidiotypic OKT3 reactivity when depleted of IgG. We urge that OKT3-treated patients be monitored routinely for IgA anti-OKT3 antibodies to avoid the expense and potential complications of retreatment with this drug in sensitized patients.

Antibodies, Anti-Idiotypic↗
PubMed1996

Alteration of the aPA ELISA by UV exposure of polystyrene microtiter plates.

Interlaboratory inconsistencies in antiphospholipid antibody (aPA) solid phase assays have prompted controversy in clinical laboratory testing for aPA. We found that the aPA ELISA can be influenced by the type of microtiter plate utilized and by the conditions in which the plates are stored. By exposing 96-well, flat-bottom polystyrene microtiter plates to short wave UV light (254 nm), the aPA ELISA signal decreased in a UV dose-dependent manner. No effect was seen with long wave UV light (366 nm). These results were independent of the antibody isotype under study or the phospholipid (PL) antigen used: anionic phosphatidylserine (PS) and cardiolipin (CL), or zwitterionic phosphatidylethanolamine (PE). Purified human beta 2-glycoprotein I (beta 2 GPI), a known cofactor for anionic PL, and rabbit anti-beta 2 GPI antisera were used to demonstrate that beta 2 GPI bound equally to UV treated and untreated microtiter plates. In contrast, recognition of beta 2 GPI on an anionic PL surface was decreased on UV treated plates, suggesting that UV exposure alters the lipid binding properties of the microliter plate. To determine whether UV exposure inhibited PL binding directly or caused a change in the way the PL was bound, the amount of PL bound to UV treated and untreated plates was measured by using fluorescent labeled PS and a fluorimeter. PS binding was decreased by 53% in UV treated wells as compared to untreated wells. These data show that short wave UV exposure reduces PL binding to polystyrene microtiter plates, thereby reducing the amount of beta 2 GPI bound to PL coated ELISA plates. Thus by using UV exposed microtiter plates, decreased or false-negative a PA ELISA results may be obtained for aPA positive plasmas.

Animals↗
PubMed1996

Antiphosphatidylethanolamine antibodies as the only antiphospholipid antibodies detected by ELISA. II. Kininogen reactivity.

OBJECTIVE: To study the requirement for serum and for low (LMWK) and high molecular weight kininogen (HMWK) and/or HMWK binding proteins to detect antiphosphatidylethanolamine antibodies (aPE) in ELISA. METHODS: Eighteen patients with aPE (9 IgG and 13 IgM) as the only antiphospholipid antibody (aPL) detected by ELISA were assigned to 4 groups: thromboembolic episodes (TEE) (Group I, n = 6); livedo reticularis (LR) without TEE, (Group II, n = 4); both LR and thrombosis (Group III, n = 4); and systemic lupus erythematosus (SLE) or primary antiphospholipid syndrome (APS) (Group IV, n = 4). All sera were analyzed in ELISA with and without bovine serum and with a purified chromatographic fraction containing LMWK, HMWK, and HMWK binding proteins. RESULTS: Eleven aPE were serum dependent: mostly IgG (7/9) and some IgM (4/13). Among the 11 serum dependent aPE, all the 7 IgG and 2 IgM were kininogen reactive. Some serum independent IgM were better detected in the absence than in the presence of serum in the ELISA. CONCLUSION: In the 18 patients, kininogens and/or HMWK binding proteins served as a "cofactor" significantly more often for aPE IgG than for aPE IgM (p = 0.007). Kininogen dependent aPE Ig were observed more often in patients with LR with or without TEE (6/8) than in those with SLE or primary APS (0/4) but this difference merely tended to significance (p = 0.06). In 2 patients, one with TEE, the other with primary APS, the IgM aPE was dependent on a serum "cofactor" that was not kininogen.

Antibodies, Antiphospholipid↗
PubMed1995

Autoantibodies to phosphatidylethanolamine (PE) recognize a kininogen-PE complex.

Demonstration of autoimmune antiphospholipid antibodies (aPA) to negatively charged phospholipids (PL) in an enzyme-linked immunosorbent assay (ELISA) requires the presence of certain phospholipid-binding plasma proteins, eg, beta 2-glycoprotein I. We found a requirement for plasma against the electrically neutral or zwitterionic phospholipid, phosphatidylethanolamine (PE). Two of these PE-binding plasma proteins were identified as high molecular weight kininogen (HMWK) and low molecular weight kininogen (LMWK). We studied anti-PE antibody (aPE) seropositive plasma from 13 patients with SLE and/or recurrent spontaneous abortions by using partially purified kininogens and kininogen binding proteins from adult bovine serum isolated by carboxymethyl (CM)-papain affinity chromatography. Eleven of 13 sera recognized a kininogen-PE complex and/or a kininogen-binding protein-kininogen-PE complex. Some aPE-positive patient sera were shown to recognize highly purified HMWK and LMWK by ELISA only when the kininogens were presented on a PE substrate. These aPE sera did not recognize PE, HMWK, or LMWK when they were presented independently as the sole antigens on the ELISA plates. Other aPE-positive sera that did not react with PE-bound HMWK or LMWK reacted with the CM-papain column eluate when it was bound to PE, which suggests that these aPE recognize factor XI or prekallikrein, which normally bind to HMWK. The aPE ELISA reactivity of two patient sera were inhibited by preincubation of the CM-papain column eluate in the ELISA plate. These data show that most aPE are not specific for PE but require the presence of certain PL-binding plasma proteins that are kininogens or proteins in complex with kininogens. Our studies indicate that aPE bind to different plasma proteins than those implicated in anionic PL, aPA ELISA reactivity.

Abortion, Habitual↗
PubMed1995

Antiphospholipid antibodies in heart transplant recipients.

Antiphospholipid antibodies (aPA) are found in patients with systemic lupus erythematosus, aPA syndrome, myocardial infarction, and stroke. The presence of aPA may predict recurrent events in certain victims of heart attack and stroke. Blood samples from 105 cardiac transplant recipients (81 men, 24 women) were tested by enzyme-linked immunosorbent assay (ELISA) for the presence of IgG, IgM, and IgA aPA to phosphatidylserine (PS), cardiolipin (CL), and phosphatidylethanolamine (PE). Patients' ages ranged from 17 to 70 years (mean 51 years). Collection times ranged from Day 1 to 9 years post transplant (mean 36 months). All patients received triple immunosuppressive therapy. We report our aPA ELISA results in multiples of the normal median (MoM) of the OD405 values calculated for 252 healthy individuals. A positive MoM is greater than the MoM that encompasses 95% of the controls; for example, above 3 MoM is considered positive for IgG anti-CL, IgA anti-PS, and CL. Above 4 MoM is positive for IgG anti-PS and PE and IgM anti-PS and CL. Thirty-nine patients had IgG anti-PS (range 4.1-14.8 MoM), 63 had IgG anti-CL (3.1-9.4 MoM), 7 had IgM anti-PS (4.1-12.1 MoM), 1 had IgM anti-CL (14 MoM), 47 had IgA anti-PS (3.1-13.1 MoM), and 58 had IgA anti-CL (3.1-11.5 MoM). In our patient population, the incidence of IgG and/or IgA aPA was significantly higher (p < 0.001) than IgM. Few patients showed specificity for either PS, CL, or PE, and many were positive with more than one antibody isotype. Because aPA were evaluated in these patients, we investigated pretransplant serum samples which are available from 79 of the 105 recipients, and found aPA in 52 of 79 (66%) patients before transplantation. Longitudinal studies were done in three patients: two had increasing IgA aPA, beginning on Days 13 and 26 post transplant, whereas the third patient showed an increased aPA on Day 8 but a decrease on Day 23. Studies are in progress to determine whether a correlation exists between the presence of aPA, immunocytochemical (biopsy) findings, and clinical outcome.

Adolescent↗
PubMed1995

Heterogeneity of the apolipoprotein H*3 allele and its role in affecting the binding of apolipoprotein H (beta 2-glycoprotein I) to anionic phospholipids.

Apolipoprotein H (apoH, protein; APOH, gene) has been implicated as a necessary cofactor for the binding of certain autoimmune antiphospholipid antibodies to anionic phospholipids. APOH exhibits genetically determined structural polymorphism with the occurrence of four alleles. Recently three IgG1k monoclonal antibodies (mAb) to human apoH, designated 3G9, 1B4, and 3D11, have been produced. The mAb 3D11 does not recognize apoH bound to anionic phospholipids in contrast to mAb 3G9 and 1B4, which recognize free and phospholipid-bound apoH. In this investigation we have determined the reactivity of the three mAb with four APOH allele products and the binding ability of these allele products with anionic phospholipids. The mAb 3G9 and 1B4, like the polyclonal anti-apoH, were equally reactive with all four allelic products, but the 3D11 recognized only the APOH*3 allele product. In the 159 APOH*3 carriers tested from five ethnic groups, the reactivity of mAb 3D11 was observed with all the Chinese but none of the African blacks. For the U.S. whites and Polynesians 89% and 75%, respectively, of the APOH*3 allele products were recognized by 3D11, while 87% of the U.S. blacks with this allele had no 3D11 reactivity. These data show that the APOH*3 allele, originally identified as a single entity by the polyclonal anti-apoH, is heterogeneous with at least one distinct variation based on mAb 3D11 reactivity. Our data also demonstrate that the apoH from certain homozygous APOH*3 individuals is unable to bind to anionic phospholipids. Such ethnic-specific apoH variations could play a significant role in the binding properties of autoimmune antiphospholipid antibodies to anionic phospholipids.

Adult↗
PubMed1995

Predictive factors in recurrent spontaneous aborters--a multicenter study.

PROBLEM: Compare data from several centers relating to success rates in recurrent spontaneous miscarriage and assess the significance of indicators of subsequent pregnancy loss. METHOD: Data from 777 couples with unexplained recurrent spontaneous abortion from independent studies at seven centers were analyzed using logistic regression analysis. The following covariates were considered: age of patient, number of previous spontaneous abortions, length of previous abortions history, sub-fertility index (defined as the product of the number of spontaneous abortions and the abortion history), whether a patient was a primary or secondary aborter, and whether a patient had received leukocyte immunotherapy. RESULTS: There was a highly significant difference between the seven centers in success rates in the subsequent pregnancy and a highly significant association between success rate and each of the following covariates: the number of previous abortions, the length of the previous abortion history and the sub-fertility index. In particular, for each increase of 10 units in the value of the sub-fertility index, up to a value of 30, the odds in favor of a successful pregnancy decreased by a factor of 0.6, i.e., 40%. There was, however, little evidence of an association between the success rate in the subsequent pregnancy and age, parity, or immunization with cells from the husband. CONCLUSIONS: The sub-fertility index may be a useful measure of likelihood of success in a subsequent pregnancy.

Abortion, Habitual↗
PubMed1994

Activity of antiphospholipid antibody ELISA cofactor in different animal sera.

A plasma protein cofactor, beta 2-glycoprotein I (beta 2GPI), also known as apolipoprotein H, is necessary to detect certain antiphospholipid antibodies (aPA) to negatively charged phospholipids (PL) in the ELISA. Inasmuch as sera are diluted 1:100 before testing, the concentration of native beta 2GPI may be insufficient to provide an optimal aPA ELISA signal. Therefore, many laboratories add adult bovine serum (ABS) to the diluent buffer to provide a consistent level of cofactor for optimal aPA binding. To determine if other animal sera can provide the cofactor, cat, chicken, dog, horse, goat, guinea pig, mouse, pig, rat, and sheep were tested as diluent supplements in the aPA ELISA. To measure cofactor activity in these animal sera, ELISA for aPA to anionic phospholipids were performed. Two aPA positive patient plasmas were selected for study; one with cofactor-dependent and one with cofactor-independent aPA. Only four of the animal sera tested (bovine, pig, sheep, and cat) supported the cofactor-dependent aPA in ELISA. The cofactor-independent aPA was positive in the presence of each animal serum except bovine and rat. In order to determine whether these animal sera contain a beta 2GPI-like molecule, Western blot analyses were performed. By using a polyclonal antiserum produced to human beta 2GPI, specific beta 2GPI-like cross-reactivity was observed with all animal sera except the chicken. In summary, cofactor activity in animal sera varied significantly; however, bovine and pig sera appear to allow optimal binding of cofactor dependent aPA.

Animals↗
PubMed1994

Increase of lymphocytes expressing Fc-receptor class III (CD16) by exposure to human seminal plasma.

OBJECTIVE: To characterize conditions for the seminal plasma-induced increase of lymphocytes that express immunoglobulin G-Fc receptor class III (Fc gamma RIII). DESIGN: Peripheral blood lymphocytes were incubated in diluted seminal plasma or control media. Cells expressing Fc gamma RIII were quantified by using flow cytometry and fluorochrome-labeled monoclonal antibodies specific for Fc gamma RIII. The influence of incubation time, temperature, and seminal plasma concentration was investigated. Physical properties of the active seminal plasma substance were characterized by studying effects of dialysis and ultracentrifugation. The origin of the active seminal plasma substance was investigated by studying activity of autopsy materials from male accessory glands. Identity of cells that are influenced by seminal plasma activity was investigated by using two-color flow cytometry with monoclonal antibodies specific for Fc gamma RIII and different phenotypic markers of leukocytes. RESULTS: Incubation of lymphocytes in seminal plasma significantly increased percentages of cells expressing Fc gamma RIII. Maximal increases were observed after seminal plasma incubation at 37 degrees C for 90 to 120 minutes and increases were significantly correlated with seminal plasma concentration. Seminal plasma activity was not altered by ultracentrifugation (100,000 x g for 30 minutes) but completely removed by dialysis (12,000 to 14,000 pore size). Fc gamma RIII-positive lymphocytes markedly increased after incubation in prostatic but not in seminal vesicle secretions. Two-color flow cytometry showed that increases of Fc gamma RIII-expressing cells occurred within the subset of CD56-positive natural killer (NK) cells. CONCLUSIONS: Dialyzable compounds of prostatic origin induce significant increases of NK cells expressing Fc gamma RIII. These findings might reflect a novel regulatory mechanism acting on CD56-positive cells within the female reproductive tract after insemination.

Analysis of Variance↗
PubMed1994

Incidence of antiphospholipid antibodies in patients with monoclonal gammopathy of undetermined significance.

The incidence of antiphospholipid antibodies in patients with monoclonal gammopathy of undetermined significance (MGUS) was studied. Antiphospholipid antibodies were measured in the sera of 93 patients (49 women, 44 men; mean age 70 [+/- 21] years) with MGUS by using an enzyme-linked immunosorbent assay (ELISA). The phospholipids tested were cardiolipin (CL), phosphatidylserine (PS), phosphatidylinositol (PI), phosphatidylglycerol (PG), phosphatidic acid (PA), phosphatidylcholine (PC), and phosphatidylethanolamine (PE). Positive results were defined as a value higher than the number of multiples of the mean per phospholipid, which included 76 of 80 (95%; 20 age-matched) control individuals. The immunoglobulin-G (IgG) or IgM antiphospholipid antibodies isotype varied among the patients, as did the phospholipid specificity. For IgG, PI was found elevated in 32% of the MGUS samples, whereas the other phospholipid antigens ranged from 9% to 15%. The percentage of patients with IgM antiphospholipid antibodies was higher. The authors observed PS, PI, PA, and PC as positive in 45%, 35%, 25%, and 25% of patients, respectively. Of the 12 sera studied for IgA isotype, three (25%) were positive for PS, six (50%) for CL, and none for PE. Patients with MGUS manifested a significantly higher (P < .01) incidence of antiphospholipid antibodies in their blood than did the control persons. No difference in the incidence of antiphospholipid antibodies was seen between younger and older (age-matched) control patients. No correlation was found between serum levels of immunoglobulins and optical density reading of the blank plates used as ELISA controls.

Aged↗
PubMed1993

Changes in beta 2-glycoprotein I antigenicity induced by phospholipid binding.

beta 2-glycoprotein I (beta 2GPI) or apolipoprotein H has been described as a necessary cofactor for antiphospholipid antibody (aPA) binding in ELISA. Some investigators disagree with the beta 2-GPI requirement whereas data from other laboratories indicate that beta 2GPI, not phospholipid (PL), is the antigen for aPA. To investigate the cofactor we have produced three IgG1 monoclonal antibodies (mAb) to human beta 2GPI; 3G9, 1B4 and 3D11. Western blot analyses showed the mAb to bind human beta 2GPI (40 kDa), but no reactivity was observed with adult or fetal bovine sera. In contrast, rabbit anti-beta 2GPI reacted with both human and bovine sera. None of the mAb reacted with phosphatidylserine (PS) or cardiolipin (CL) by ELISA. There were no significant differences in ELISA binding to purified beta 2GPI when the mAb were adjusted to the same concentration. mAb 3G9 and 1B4 gave stronger signals in ELISA after beta 2GPI bound to PS; the increase for 3G9 was significantly greater than for 1B4 (p < 0.002). mAb 3D11 was unique inasmuch as it failed to recognize beta 2PGI bound to PS. In comparison, the rabbit anti-beta 2GPI was unaffected by PS-beta 2GPI binding. These observations indicate that the mAb recognize three distinct epitopes on beta 2GPI. The data suggest that beta 2GPI undergoes conformational changes subsequent to binding PL. Our findings are consistent with the hypothesis that aPA recognize a beta 2GPI neotope formed subsequent to binding PL.

Animals↗