Antibodies binding to anionic phospholipids but not to oxidized low-density lipoprotein are associated with thrombosis in patients with systemic lupus erythematosus

OBJECTIVE

Elevated levels of antibodies against oxidized low-density lipoprotein (LDL) frequently occur in patients with systemic lupus erythematosus (SLE) and these antibodies crossreact in many sera with anticardiolipin antibodies, known to be associated with thrombosis. Therefore, a study was carried out to assess the mutual relationship between antibodies against oxidized LDL and thrombosis.

METHODS

The occurrence of IgG class antibodies against oxidized LDL, cardiolipin and phosphatidyl serine were determined by enzyme-linked immunosorbent assay in a series of 146 patients with SLE. Twenty-one patients had had thromboembolic complications. At least one of three tests used to detect lupus anticoagulant was positive in 34 out of 133 patients.

RESULTS

The level of antibodies against oxidized LDL correlated significantly with that of antibodies against cardiolipin (r = 0.52) but only marginally with antibodies against phosphatidyl serine (r = 0.18). Antibodies against cardiolipin and phosphatidyl serine, but not those against oxidized LDL, were significantly associated with the presence of lupus anticoagulant (odds ratios of the risk in the highest tertile relative to the lower tertiles of the antibody were 5.3, 6.9 and 1.1, respectively) and with thrombosis (odds ratios 2.5, 4.0 and 1.0, respectively).

CONCLUSION

The observations suggest that only those antibodies reacting specifically with cardiolipin and phosphatidyl serine are associated with thrombosis and with the presence of lupus anticoagulant in patients with SLE, whereas antibodies crossreacting with oxidized LDL and those reacting specifically with oxidized LDL are not associated.

Antibodies to phospholipid-binding plasma proteins and occurrence of thrombosis in patients with systemic lupus erythematosus

There is accumulating evidence that anti-phospholipid (aPL) antibodies in the sera of patients with autoimmune diseases bind to a complex of anionic phospholipids and plasma phospholipid-binding proteins, namely beta 2-glycoprotein I (beta 2-GPI) and prothrombin. It has been suggested that a conformational change in beta 2-GPI, induced by binding either to anionic phospholipids or to the oxygen molecules on the irradiated microtiter plate, reveals cryptic antigenic epitope(s) in the native protein. We used an enzyme-linked immunoassay for measuring antibodies against two phospholipid-binding proteins, i.e., beta 2-GPI and prothrombin, absorbed to an irradiated plate in an unselected series of 139 patients with systemic lupus erythematosus (SLE). Elevated levels of antibodies against beta 2-GPI were found in 49% of patients and antibodies against prothrombin in 34% of patients. Both antibodies were significantly associated with deep venous thrombosis in patients with SLE (P = 0.009 for both antibodies). Accordingly, testing of these antibodies seems to be clinically useful in evaluating the risk of thrombosis.

Effect of cetirizine on the inflammatory cells in mosquito bites

BACKGROUND

Mosquito bites frequently cause wealing and delayed papules which appear within a few hours after the bites and may persist for several days. Cetirizine is an effective drug against mosquito bites by decreasing wealing and also the size and pruritus of the delayed bite papules.

OBJECTIVES

To characterize inflammatory cells in the delayed mosquito-bite lesions, and to study the effect of cetirizine on the inflammatory cell response.

METHODS

Twenty-six mosquito-bite sensitive subjects received cetirizine 20 mg (14 subjects) or placebo (12 subjects) in a double-blind fashion. Aedes aegypti-bites were given on a forearm and serial punch biopsies were taken at 2-, 6- and 24h after the bite exposure. Eosinophils, neutrophils, mast cells, mononuclear cells and T- helper (CD4+) and suppressor (CD8+) lymphocytes were counted from dermal infiltrates.

RESULTS

Eosinophils and neutrophils were found already in 2-h bite lesions. Moreover, the number of mononuclear and CD4+ cells increased significantly (P < 0.01) from 2- to 24-h bite lesions. Unexpectedly, the overall numbers of eosinophils (P < 0.05), mononuclear cells (P < 0.01) and CD4+ cells (P < 0.01) were significantly higher in the cetirizine-treated subjects compared with the placebo-treated subjects.

CONCLUSIONS

The results suggest that the inflammatory cell response in the delayed mosquito-bite lesions is similar to that occurring in allergic late-phase responses, i.e. an early influx of eosinophils, neutrophils and subsequent accumalation of CD4+ lymphocytes. The reason for the high numbers of eosinophils and CD4+ cells in the cetirizine-treated subjects is not known.

Affinity-purified cardiolipin-binding antibodies show heterogeneity in their binding to oxidized low-density lipoprotein

Antiphospholipid antibodies in autoimmune sera have been shown to react with a complex of phospholipids (cardiolipin) and a plasma phospholipid-binding protein, beta 2-glycoprotein I (apolipoprotein H). The binding of these antibodies was inhibited by oxidized low-density lipoprotein (LDL) in sera from patients with systemic lupus erythematosus (SLE), suggesting cross-reactivity between antiphospholipid antibodies and antibodies binding to oxidized LDL. We purified antiphospholipid antibodies by cardiolipin-polyacrylamide column from seven SLE sera and studied the reactivity of eluted fractions with cardiolipin-beta 2-glycoprotein I complex and oxidized LDL (malondialdehyde-conjugated LDL) in solid-phase enzyme immunoassay. In four sera the binding of IgG antibodies to cardiolipin-beta 2-glycoprotein I complex and to oxidized LDL appeared in the same fractions, whereas in three sera reactivities against cardiolipin and oxidized LDL were observed, at least in part, in separate fractions. The binding to solid-phase cardiolipin was dependent on the presence of exogenous beta 2-glycoprotein I in all fractions. Our findings show that antiphospholipid antibodies are heterogeneous in their binding to oxidized LDL, indicating that these two antibodies may have different subspecificities. Some eluted fractions reacted only with oxidized LDL, and did not show binding to cardiolipin-beta 2-glycoprotein I complex, suggesting that the lipid part in the antigenic complex might be responsible for the cross-reactivity of these antibodies. Accordingly, the biological functions of antibodies against phospholipid-beta 2-glycoprotein I complex and antibodies against oxidized LDL may also be different.

Significance of rubber elongation factor as a latex allergen

IgE-mediated hypersensitivity to proteins eluting from surgical gloves and other natural rubber products is a well-recognized allergic condition with special impact to health care workers and sensitized patients. Since rubber elongation factor (REF) has been suggested to be the major latex allergen (Hev b 1) we purified REF from rubber particles using electrophoresis and electroelution and reevaluated the occurrence of IgE antibodies to purified REF. The purified protein was subjected to tryptic digestion, peptide separation and amino acid sequencing. Amino acid sequences of 9 tryptic peptides from the purified 14-kD protein gave 100% homology to REF. In immunoblotting, sera from 4 of 6 latex-allergic children with spina bifida or other congenital anomalies exhibited IgE antibodies against REF whereas only 1 serum from the 30 other latex-allergic patients had similar antibodies. In IgE ELISA 8/45 (18%) latex-allergic patients had IgE antibodies to purified REF, whereas 30 (67%) of the same patients had IgE antibodies to purified prohevein, another rubber protein, recently shown to be a major natural rubber latex allergen. The observed overall low frequency of IgE antibodies to purified REF, as measured by two specific IgE assays, indicates that REF is one but not the most significant allergen among the natural rubber latex proteins.

Crossreactivity between allergens in natural rubber latex and banana studied by immunoblot inhibition

BACKGROUND

An association between allergic reactions to natural rubber latex and to banana has been reported but the immunochemical properties of the putative cross-reacting allergens remain unknown.

OBJECTIVE

To study extracts of banana and natural rubber latex and sera from latex-allergic patients for possible crossreacting allergens and IgE antibodies.

METHODS

Sera from 22 latex-allergic patients and 22 control subjects with no evidence of allergy to latex or to banana were studied. All patients had positive and controls negative reactions in skin-prick testing using an eluate of latex gloves. IgE antibodies to natural rubber latex and to banana were evaluated by immunoblotting and by radioallergosorbent test (RAST) and crossreactivity between allergens in banana and natural rubber latex by immunoblot inhibition. Skin-prick testing was used to examine in vivo reactivity to banana.

RESULTS

Ten of the 22 (45%) latex-allergic patients sera recognized altogether 14 allergens in banana by immunoblotting. The most frequently identified banana allergens were 23, 32, 36, 39 and 47 kDa proteins. The banana skin-prick test was positive in 14 of 18 (78%) latex-allergic patients studied and banana RAST in 12 of 14 patient sera tested. Fourteen of 21 interviewed patients reported symptoms from eating or handling bananas. In immunoblot inhibition studies a dose-dependent inhibition of IgE binding to banana extract with natural rubber latex proteins was observed in all five patient sera tested and, likewise, the binding of IgE to natural rubber latex extract was inhibited with banana proteins in four of the five patient sera.

CONCLUSIONS

The present results confirm the existence of crossreacting allergens in natural rubber latex and banana and provide new information on the immunochemical nature and heterogeneity of these allergens.

Antibodies to prothrombin imply a risk of myocardial infarction in middle-aged men

Antiphospholipid antibodies in patients with "antiphospholipid syndrome" may be directed at least in part against plasma phospholipid-binding proteins, such as beta 2-glycoprotein I or prothrombin, which are involved in the control of thrombosis and haemostasis. IgG-class antibodies against prothrombin and beta 2-glycoprotein I were measured by enzyme-linked immunoassay in initially healthy middle-aged dyslipidaemic men (non-high-density lipoprotein > 5.2 mml/l). Serum samples had been drawn at entry to a 5-year coronary primary-prevention trial with gemfibrozil from 106 subjects who experienced either a non-fatal myocardial infarction or cardiac death during the follow-up and from 106 subjects without coronary episodes, matched for treatment group (gemfibrozil/placebo) and geographical area. The antiprothrombin antibody level, as expressed in optical density units, was significantly higher in patients than in controls (0.26 +/- 0.17 versus 0.22 +/- 0.09; p < 0.02). A high level of antiprothrombin antibodies (highest tertile of distribution) predicted a 2.5-fold increase in the risk (95% confidence interval 1.2-5.3) of myocardial infarction or cardiac death. The distribution of IgG-class antibodies against beta 2-glycoprotein I did not differ significantly between cases and controls. The joint effect of antiprothrombin antibodies and other factors associated with hypercoagulative state: triglyceride level, lipoprotein(a) and smoking, was multiplicative for the risk. Antiprothrombin antibodies are a new immunological predictor of myocardial infarction and the effect of these antibodies may be mediated by hypercoagulative mechanisms.

The main IgE-binding epitope of a major latex allergen, prohevein, is present in its N-terminal 43-amino acid fragment, hevein

Polypeptides of natural rubber latex (NRL) that elute from surgeon's gloves and other manufactured rubber products can sensitize exposed individuals and elicit severe hypersensitivity reactions. Previously, we showed that prohevein is a major allergen in NRL, the source material for rubber manufacturing. To analyze which region of the molecule carries the main IgE-binding epitope(s), we purified prohevein and its C-domain from NRL by gel filtration, reverse phase chromatography, and electroelution. In immunoblotting, prohevein bound IgE from 15 of 20 (75%), and the prohevein C-domain from 3 of 20 (15%) latex-allergic patient sera. In ELISA, 36 of 52 (69%) patient sera showed IgE binding to prohevein, whereas 11 of 52 (21%) sera had IgE to prohevein C-domain. We then purified from a brand of highly allergenic surgeon's gloves six hydrophilic peptides that revealed in amino-terminal sequencing 100% identity to the N-terminus of prohevein. In mass spectrometry, all purified peptides gave a molecular mass of 4719 +/- 1.9 daltons, which corresponds to the molecular mass of hevein (4719.1 daltons), a 43-amino acid N-terminal fragment of prohevein. Purified hevein inhibited 72% of IgE binding from pooled sera of NRL-allergic patients to solid phase glove extract and 45% of IgE binding to solid phase NRL. Of the 43 NRL-allergic patient sera tested, 56% showed IgE Abs to purified hevein in ELISA. In skin prick testing, purified hevein elicited positive reactions in three-quarters of the latex-allergic patients tested. These results indicate that the majority of prohevein's IgE-binding ability resides in its N-terminal fragment, known as hevein. In one highly allergenic latex glove examined, the majority of IgE-binding ability was attributable to hevein molecules, suggesting that these peptides can be significant sensitizers in NRL allergy.

The main IgE-binding epitope of a major latex allergen, prohevein, is present in its N-terminal 43-amino acid fragment, hevein

Polypeptides of natural rubber latex (NRL) that elute from surgeon's gloves and other manufactured rubber products can sensitize exposed individuals and elicit severe hypersensitivity reactions. Previously, we showed that prohevein is a major allergen in NRL, the source material for rubber manufacturing. To analyze which region of the molecule carries the main IgE-binding epitope(s), we purified prohevein and its C-domain from NRL by gel filtration, reverse phase chromatography, and electroelution. In immunoblotting, prohevein bound IgE from 15 of 20 (75%), and the prohevein C-domain from 3 of 20 (15%) latex-allergic patient sera. In ELISA, 36 of 52 (69%) patient sera showed IgE binding to prohevein, whereas 11 of 52 (21%) sera had IgE to prohevein C-domain. We then purified from a brand of highly allergenic surgeon's gloves six hydrophilic peptides that revealed in amino-terminal sequencing 100% identity to the N-terminus of prohevein. In mass spectrometry, all purified peptides gave a molecular mass of 4719 +/- 1.9 daltons, which corresponds to the molecular mass of hevein (4719.1 daltons), a 43-amino acid N-terminal fragment of prohevein. Purified hevein inhibited 72% of IgE binding from pooled sera of NRL-allergic patients to solid phase glove extract and 45% of IgE binding to solid phase NRL. Of the 43 NRL-allergic patient sera tested, 56% showed IgE Abs to purified hevein in ELISA. In skin prick testing, purified hevein elicited positive reactions in three-quarters of the latex-allergic patients tested. These results indicate that the majority of prohevein's IgE-binding ability resides in its N-terminal fragment, known as hevein. In one highly allergenic latex glove examined, the majority of IgE-binding ability was attributable to hevein molecules, suggesting that these peptides can be significant sensitizers in NRL allergy.

Prognostic value of quantitative measurement of rheumatoid factor in early rheumatoid arthritis

The prognostic value of quantitative measurement of rheumatoid factor (RF) by immunoturbidimetry was evaluated in 78 patients with early rheumatoid arthritis (RA) during a 3-yr follow-up. After starting disease-modifying antirheumatic treatment, a significant improvement in conventional clinical and laboratory variables measuring disease activity was observed, while a steady increase was found in radiological progression. Initial RF levels correlated with radiologically determined joint damage up to 3 yr, whereas no correlation of other initially determined conventional variables of disease activity was found. High levels of RF at entry and persistent RF positivity during the follow-up were markers for destructive disease. Initial RF positivity alone was a sensitive predictor for later joint destruction, but quantitative measurement of the initial RF level and especially repeated measurements of RF seemed to add significantly to the prognostic value of RF in distinguishing between progressive and non-progressive disease in early RA.

Antibodies to oxidized low-density lipoprotein and to cardiolipin in nonpregnant and pregnant women with habitual abortion

OBJECTIVE

To determine the occurrence of antibodies to oxidized low-density lipoprotein (LDL) in women with a history of habitual abortion before and during pregnancy.

DESIGN

Immunoglobulin G class antibodies to malondialdehyde modified LDL were determined by a solid-phase ELISA in 42 habitual aborters before pregnancy, in 39 patients during pregnancy, and in 23 comparable nonpregnant and 22 pregnant control women without a history of abortion. In addition, we assessed the presence of anticardiolipin antibodies by ELISA in the same sera.

SETTING

Departments I and II of Obstetrics and Gynecology, University Central Hospital of Helsinki, Helsinki, Finland.

RESULTS

Early pregnancy was accompanied by a decrease in the median levels of antibodies to oxidized LDL both in habitual aborters and in the control series. Only one patient exhibited a raised level of antibodies to oxidized LDL before pregnancy but, during pregnancy, nine patients (23%) had elevated levels of antibodies to oxidized LDL, similar to women with a favorable outcome of pregnancy (6/27, 22%) and in women whose current pregnancy also ended in abortion (3/12, 25%). Cardiolipin binding antibodies were detected in three habitual aborters before pregnancy (7%) and in nine women during pregnancy (23%), with a tendency to be more frequent in patients with miscarrying pregnancies than in those with continuing pregnancies (4/12, 33% and 5/27, 19%). Antibodies to oxidized LDL and cardiolipin were simultaneously present in three habitual aborters with continuing pregnancies.

CONCLUSIONS

Increased levels of antibodies to oxidized LDL and cardiolipin may be associated with habitual abortion.

Cross-reacting allergens in natural rubber latex and avocado

BACKGROUND

An association between allergy to latex and avocado has been reported but the responsible cross-reacting allergens have not been identified or characterized.

METHODS

Immunoblotting, immunoblot inhibition, and RAST inhibition methods were used to study cross-reactive proteins between natural rubber latex (NRL) and avocado. Sera from 18 patients with previously verified latex allergy were used as the source of IgE antibodies, and 11 of the patients underwent skin prick testing with fresh avocado.

RESULTS

Fourteen of the 18 sera (78%) had IgE antibodies that bound to a total of 17 avocado proteins with apparent molecular weights ranging from 16 to 91 kd. Ten most strongly reacting sera were used for immunoblot inhibition studies. When NRL proteins were used as soluble inhibitors, binding of IgE antibodies to solid-phase avocado proteins was inhibited in a dose-dependent manner: 100 micrograms of NRL proteins inhibited IgE binding to 15 of the 17 avocado proteins, and 10 micrograms caused inhibition to 13 protein bands. Comparably, soluble avocado proteins were able to inhibit IgE binding to solid-phase NRL. Corresponding RAST inhibitions were performed with two patient sera; in both, avocado inhibited IgE binding to NRL and in one NRL proteins inhibited IgE binding to avocado. Skin prick test responses to fresh avocado were positive in seven of the 11 patients with latex allergy who were tested.

CONCLUSIONS

The large number of inhibitable proteins in immunoblot experiments and clinical observations from skin prick tests suggest considerable immunologic cross-reactivity between NRL and avocado. The observed cross-reacting protein components may be responsible for the recently reported type I hypersensitivity reactions to NRL and avocado in patients with a preexisting allergy to either allergen.

Prohevein from the rubber tree (Hevea brasiliensis) is a major latex allergen

BACKGROUND

There is general agreement that proteins eluting from different natural rubber latex products can cause immediate type hypersensitivity reactions in latex-allergic patients. However, there is as yet no consensus as to what are the most important allergens in natural rubber latex.

OBJECTIVE

We wanted to purify and characterize at the primary structure level three natural latex proteins, suggested to represent significant allergens.

METHODS

Proteins were purified from ultracentrifuged bottom fraction of natural rubber latex using high performance liquid chromatography gel filtration and reversed phase chromatography. Purified proteins were subjected to tryptic cleavage, peptide separation and amino acid sequencing. Immunoblotting was used to demonstrate IgE antibodies to the purified proteins in sera from latex-allergic patients.

RESULTS

A 20 kDa protein was identified by amino acid sequencing as prohevein, a major protein in the rubber tree Hevea brasiliensis, and a 30 kDa natural rubber latex protein as hevamine, another essential rubber tree protein. A third, previously undescribed natural rubber latex protein, showed high homology to several plant endo-1,3-beta-glucosidases. In immunoblotting, the purified prohevein bound IgE antibodies from 24/29 (83%) sera of latex-allergic patients including positive results in 4/6 latex-allergic children with spina bifida or other congenital anomalies. The purified prohevein elicited positive skin-prick test reactions in all six latex-allergic patients showing IgE to prohevein. The purified 36 kDa protein bound IgE from 6/29 (21%) latex-allergic sera, and the purified hevamine from only 1/29 patient sera.

CONCLUSION

The observed high frequency of IgE antibodies to prohevein suggests that this protein is a major natural rubber latex allergen.

IgM class autoantibodies in human cord serum

It has previously been shown that human neonatal B lymphocytes in vitro can synthesize autoantibodies which typically are of IgM class, polyreactive and of low affinity and thought to represent natural autoantibodies. We screened 1034 cord serum specimens to find sera with elevated IgM levels; 98 such sera were further examined by an enzyme-linked immunosorbent assay (ELISA) to determine whether antibodies against a panel of autoantigens could be found. We detected low levels of IgM class antibodies against cardiolipin, pyruvate dehydrogenase, single-stranded DNA, thyroglobulin and Fc fragments of IgG as rheumatoid factors. The IgM concentration correlated with autoantibody levels. The specificity of the autoantibody assays was confirmed by inhibition tests. We conclude that several types of autoantibodies can be found in some sera of newborns and that increased IgM concentration of some neonates may reflect a polyclonal antibody response.

Purification and partial amino acid sequencing of a 27-kD natural rubber allergen recognized by latex-allergic children with spina bifida

We purified from natural rubber latex (NRL) by means of high-performance liquid chromatography a 27-kD protein, recognized characteristically by IgE in sera from latex-allergic children with spina bifida or other congenital anomalies and histories of multiple surgeries. N-terminal sequence analysis of the purified 27-kD protein was unsuccessful suggesting that its N-terminus is blocked. To obtain internal sequence information from the protein it was digested with trypsin and the purified tryptic peptides were subjected to sequence analysis. Thirteen of the 14 sequenced peptides revealed no significant homology to any of the published protein sequences indicating that the 27-kD protein is previously undescribed at the primary structure level. However, one of the 14 sequenced peptides showed significant homology to the rubber elongation factor, a 14.6-kD NRL protein. For the time being, the 27-kD NRL protein is the first molecularly characterized NRL allergen associated with defined clinical manifestations of latex allergy.

Antibodies against oxidised low-density lipoprotein in juvenile chronic arthritis

Enhanced lipid peroxidation, reported to take place in rheumatoid joints and suggested to play a significant role in joint inflammation, led us to study the occurrence of antibodies against oxidised low-density lipoprotein (Ox-LDL Ab) in patients with juvenile chronic arthritis. Enzyme-linked immunosorbent assay was used to detect Ox-LDL Ab and antiphospholipid antibodies (aPL Ab) in sera from 84 patients and 91 controls. Elevated levels of Ox-LDL Ab were found in 14 patients (17%) as opposed to 4 controls (4%; p < 0.01). Similarly, 14 patients had an elevated aPL Ab level and a fairly good correlation between Ox-LDL Ab and aPL Ab (r = 0.52) existed in the patients. The increased frequency of elevated levels of Ox-LDL Ab may reflect lipid peroxidation occurring in rheumatoid joints but crossreactivity with aPL Ab for the induction of Ox-LDL Ab cannot be excluded.

Fetal outcome in women with primary Sjögren's syndrome. A retrospective case-control study

OBJECTIVE

To study fetal outcome in women with primary Sjögren's syndrome (SS) compared to that in women with systemic lupus erythematosus (SLE) and healthy women, and to study the possible association of fetal loss with anticardiolipin antibodies (aCL) and antibodies to SS-A/Ro and SS-B/La in women with primary SS.

METHODS

A retrospective analysis of the fetal outcome in 55 pregnancies in 21 patients with primary SS compared to that in 100 pregnancies in 42 patients with SLE and 94 pregnancies in 42 healthy women matched for age, parity and the onset of the autoimmune disease with respect to pregnancy. IgG-, IgM- and IgA-aCL were determined by a cofactor-dependent ELISA and antibodies to SS-A/Ro and SS-B/La by ELISA using human recombinant antigens and affinity-purified antigens.

RESULTS

Of all the 55 pregnancies in patients with primary SS, 8 (15%) occurred after the onset of primary SS symptoms. Eleven (20%) of the 55 pregnancies ended in fetal loss. The relative risk (RR) for fetal loss in patients with primary SS was 2.7 (95% CI 1.1-6.5; p = 0.023), and after the exclusion of the patient with four spontaneous abortions it was 2.0 (0.7-5.3; p = 0.18). In SLE the level of risk was 2.2 (0.9-5.0; p = 0.065). Fetal loss in patients with primary SS was not associated with elevated levels of anticardiolipin antibodies (aCL) or autoantibodies to SS-A/Ro or SS-B/La. Newborns of mothers with primary SS were not more premature or growth retarded than newborns of healthy women, but the absolute and the relative birth weights of the newborns of mothers with SLE was significantly lower than in healthy controls (P < 0.001 and P < 0.0001, respectively).

CONCLUSION

We conclude that the majority of pregnancies in women with primary SS occur before the onset of the disease and that these women have an increased risk of fetal loss, which is not associated with elevated levels of ACL or antibodies to SS-A/Ro or SS-B/La. The risk of fetal loss in primary SS is similar to that in women with SLE, but fetal growth retardation appears to be more common in SLE than in primary SS.

Anti-cardiolipin antibodies and risk of myocardial infarction in a prospective cohort of middle-aged men

BACKGROUND

Data concerning the relation between antiphospholipid (aPL) antibodies and myocardial infarction in subjects without evidence of overt autoimmune disease are conflicting. All published studies have been performed on survivors of myocardial infarction or in patients with established coronary heart disease. The purpose of the present study was to determine whether the presence of aPL antibodies, namely, anti-cardiolipin (aCL) antibodies, carries a risk for myocardial infarction in a prospective cohort.

METHODS AND RESULTS

The sera to be studied were drawn at entry from middle-aged dyslipidemic men (non-high-density lipoprotein cholesterol, > or = 5.2 mmol/L) participating in the Helsinki Heart Study, a 5-year coronary primary prevention trial with gemfibrozil. Samples were tested for IgG-class antibodies to cardiolipin by an ELISA. The risk was estimated with logistic regression analysis using a nested case-control design with 133 patients (myocardial infarction or cardiac death) and 133 control subjects, matched for treatment (gemfibrozil/placebo) and geographical area. The aCL antibody level, as expressed in optical density units, was significantly higher in patients than in control subjects (0.417 versus 0.361; P < .005). Subjects with the antibody level in the highest quartile of distribution had a relative risk for myocardial infarction of 2.0 (95% confidence interval, 1.1 to 3.5) compared with the remainder of the population. This risk was independent of confounding factors, such as age, smoking, systolic blood pressure, low-density lipoprotein (LDL), and high-density lipoprotein. There was a correlation between the levels of aCL antibodies and antibodies to oxidized LDL (r = .40, P < .001), and their joint effect was additive for the risk.

CONCLUSIONS

In a prospective cohort of healthy middle-aged men, the presence of a high aCL antibody level is an independent risk factor for myocardial infarction or cardiac death. Antibodies to cardiolipin and oxidized LDL may, at least in part, represent cross-reactive antibody populations.

Serum ferritin and ceruloplasmin as coronary risk factors

Iron and copper catalyze lipid peroxidation in vitro, and recent epidemiological data suggest that these metal ions might also be involved in human coronary heart disease. We tested the hypothesis by investigating whether the storage proteins ferritin and ceruloplasmin were coronary risk factors. A nested case-control study was set up in middle-aged dyslipidaemic participants of the Helsinki Heart Study: a placebo-controlled coronary primary prevention trial with gemfibrozil. Of the 140 subjects with cardiac end-points (non-fatal myocardial infarction or cardiac death) 136 were matched with controls for geographical area and drug treatment (gemfibrozil-placebo). Frozen baseline serum samples were used in the analyses of ferritin and ceruloplasmin. Using logistic regression analyses no increment in coronary risk was detected with increasing ferritin levels (P = 0.8 for trend). Ceruloplasmin was higher 349 +/- 86 vs 317 +/- 77 mg.l-1 (P < 0.001) in cases than in controls and the risk in the highest tertile was two-fold (odds ratio 2.1; 95% CI 1.1-4.2) compared to the lowest (P < 0.005 for trend). The risk of high ceruloplasmin was influenced by lipoprotein cholesterol concentrations, with an odds ratio of 2.4 (95% CI 1.3-4.4) in subjects with high low density lipoprotein cholesterol and of 11.3 (95% CI 2.5-52.2) in subjects with low high density lipoprotein cholesterol. It was concluded that ferritin was not associated with coronary heart disease in dyslipidaemic, middle-aged men, while there was a continuous and graded increment in coronary risk with elevating ceruloplasmin level.

Antibody against oxidized low-density lipoprotein predicting myocardial infarction

BACKGROUND

Oxidation of low-density lipoprotein is believed to be an important step in the pathogenesis of atherosclerosis. The purpose of the present study was to determine whether antibody against oxidized low-density lipoprotein, reported to be associated with the progression of carotid atherosclerosis, is predictive of cardiac death and nonfatal myocardial infarction.

METHODS

Serum samples from 135 cases and their controls, drawn at entry from middle-aged dyslipidemic men participating in the Helsinki Heart Study, a 5-year coronary primary prevention trial with gemfibrozil, were tested for immunoglobulin G class antibodies against oxidized low-density lipoprotein by enzyme-linked immunosorbent assay.

RESULTS

The mean antibody level, expressed in optical density units, was significantly higher in cases than in controls (0.412 vs 0.356, P = .002). After adjustment for age, smoking, blood pressure, and high-density lipoprotein cholesterol level, there was a 2.5-fold increased risk (95% confidence interval, 1.3 to 4.9) of a cardiac end point in the highest tertile of antibody level vs the lowest tertile (P = .005 for trend).

CONCLUSIONS

Elevated levels of antibodies against oxidized low-density lipoprotein were predictive of myocardial infarction. The effect was independent of low-density lipoprotein cholesterol levels, and the joint effect was additive. Elevated antibody levels modified the effects of classic coronary risk factors.

Passive transfer of cutaneous mosquito-bite hypersensitivity by IgE anti-saliva antibodies

BACKGROUND

Mosquito bites frequently cause cutaneous wheal and flare reactions, and recent immunoblotting studies have shown specific anti-saliva IgE antibodies in many persons who have such reactions.

OBJECTIVE

The study was designed to show that human serum containing mosquito saliva-specific IgE antibodies can produce histamine release in vitro and whealing in vivo.

METHODS

Two mosquito bite-tolerant subjects had bite challenges and Prausnitz-Küstner tests with heated and unheated serum from one patient with Aedes mosquito allergy. Immunoblotting and basophil histamine release tests were performed with the patient's and subjects' sera.

RESULTS

Both mosquito bite-tolerant subjects had positive Prausnitz-Küstner reactions, which indicated a successful transfer of cutaneous mosquito hypersensitivity. The ordinary and passive basophil histamine release tests also produced positive results with Aedes communis antigens.

CONCLUSION

The results of the Prausnitz-Küstner test, immunoblotting, and basophil histamine release tests are consistent with the hypothesis that mosquito bite whealing is mediated by specific anti-saliva IgE antibodies.