Avidin is a promising tag for fusion proteins produced in baculovirus-infected insect cells

The baculovirus expression vector system (BEVS) has become one of the most versatile and powerful eukaryotic systems for recombinant protein expression. We have constructed a novel baculovirus transfer vector (pbacAVs+C) which allows for the efficient production, detection, and single-step purification of the desired molecule as a secretion-compatible avidin fusion protein in insect cells. It also enables fast construction of the baculoviruses by site-specific transposition in Escherichia coli. To demonstrate the power of this vector, we report here on the production of immunologically intact hevein, a major cysteine-rich latex allergen, as avidin fusion protein. Our results indicate that avidin is a stable and versatile tag in the BEVS. It retains its extraordinarily high biotin-binding activity and also enables independent folding of the fusion partner. The versatility with which avidin fusion proteins can be detected, purified, and immobilized is the basis for the use of our system as a useful alternative in eukaryotic fusion protein production.

Cow's milk casein, a hidden allergen in natural rubber latex gloves

BACKGROUND

We have previously noted that one natural rubber latex (NRL) glove brand used for skin prick testing in the diagnosis of NRL allergy contained cow's milk casein.

OBJECTIVE

We sought to examine whether other commonly marketed NRL glove brands contain cow's milk casein.

METHODS

The casein content of 30 NRL glove extracts (1:5 wt/vol) was measured by RAST inhibition and by rocket immunoelectrophoresis and rocket radioimmunoelectrophoresis by using casein-specific rabbit antiserum, a serum pool from patients with cow's milk allergy, and radiolabeled anti-human IgE. The NRL allergen content was measured by ELISA inhibition.

RESULTS

The casein content of the glove used in NRL allergy screening (Triflex, Baxter) was rather high (ie, about 400 microgram/g of glove). Its total protein content was 1000 microgram/g of glove. Rocket radioimmunoelectrophoresis detected distinct amounts of casein in 8, minimal amounts in 7, and no casein in the remaining 15 NRL glove brands.

CONCLUSIONS

Several brands of NRL gloves were found to contain casein, implying that extracts prepared from such gloves can cause false-positive skin prick test reactions when diagnosing NRL allergy. The use of casein as a stabilizer in glove manufacture without appropriate labeling should be stopped because it can also cause contact urticaria syndrome in individuals with cow's milk allergy.

Increased allergen production in turnip (Brassica rapa) by treatments activating defense mechanisms

BACKGROUND

Practical applications to enhance the productivity of agriculture by using plants with improved resistance to pathogens are expected to increase in the near future. Defense proteins play an important role in pathogen resistance, and some defense-related proteins are significant cross-reacting allergens. For example, cross-allergies are common among patients allergic to natural rubber latex (NRL), which contains many defense-related proteins.

OBJECTIVE

Using a model plant (ie, turnip), we studied whether allergen contents increase after treatments activating defense mechanisms of the plants.

METHODS

Whole or wounded turnips treated with salicylic acid, ethephon, or water were incubated for 2, 4, or 8 days. Allergen content was investigated by IgE immunoblotting with sera from patients allergic to NRL. An induced protein that bound IgE most intensively was purified and further characterized by mass analysis, amino acid sequencing, IgE-ELISA, and skin prick tests.

RESULTS

In immunoblotting, clear IgE-binding bands were discernible only in samples from chemically treated plants. IgE was bound most intensively to a protein with an apparent molecular weight of 25 kd in SDS-PAGE and with a determined molecular weight of 18.7 kd. Sequenced peptides of the 18.7-kd protein showed over 70% homology to prohevein, a major allergen of NRL, and to many other prohevein-like defense proteins. In ELISA, sera from 30 of 34 (88%) adults and 21 of 26 (81%) children previously shown to have IgE against prohevein bound to the purified protein. In skin prick testing with the protein, 4 of 6 patients allergic to NRL had positive reactions.

CONCLUSION

These results demonstrate that activating defense mechanisms of plants may considerably increase their allergen content.

Antifilaggrin antibodies in recent-onset arthritis

We evaluated the sensitivity and prognostic value of an enzyme-linked immunosorbent assay (ELISA) for the measurement of antifilaggrin antibodies (AFA), using filaggrin purified from human skin as an antigen. The AFA test was applied to a series of 306 patients with various recent-onset inflammatory joint diseases. The results were compared to those of the conventional immunofluorescence tests for antikeratin antibody (AKA) and antiperinuclear factor (APF) and of the rheumatoid factor (RF) tests from a previous study. There was a very good agreement between the results of the tests for APF and AFA (kappa-value 0.79 in patients with peripheral poly/oligoarthritis). The agreement between the tests for AKA and AFA was significant but less pronounced (kappa-value 0.50). The AFA test detected 10/22 of the RF-negative erosive cases, particularly those with a large number of erosive joints. Thus, the test for AFA supplements RF in the prediction of erosiveness.

Identification of patatin as a novel allergen for children with positive skin prick test responses to raw potato

BACKGROUND

Peeling of raw potatoes may cause allergic symptoms, such as sneezing, wheezing, and contact urticaria, for adults. For children, potatoes as food may cause various allergic reactions. However, the identity and molecular structure of the putative allergens in potato have remained unknown.

OBJECTIVE

The aim of our study was to identify possible major allergens in potato by using sera of atopic children suspected of having food allergy and having positive skin prick test responses to raw potato.

METHODS

Potato proteins were purified by standard methods of protein chemistry and characterized with amino-terminal sequencing and mass spectrometry. The IgE-binding ability of the purified proteins was verified by immunoblotting and ELISA with IgE antibodies from the sera of atopic children having positive skin prick test responses to raw potato.

RESULTS

Immunoblotting showed strong IgE binding to a 43-kd protein, identified as patatin, the main storage protein of potato tubers. In ELISA, 20 of 27 (74%) children with positive skin prick test responses to potato and none of the control subjects showed specific binding of IgE antibodies to purified patatin. A positive wheal-and-flare reaction was seen in 8 of 14 children prick tested with purified patatin.

CONCLUSION

These results show that patatin in potatoes is a significant, previously unrecognized,IgE-binding protein for children with a positive skin prick test response to raw potato. Further studies are needed to confirm the clinical importance of potatoes, and especially patatin, as a food allergen.

Hevein-like protein domains as a possible cause for allergen cross-reactivity between latex and banana

BACKGROUND

Patients allergic to natural rubber latex (NRL) frequently exhibit immediate hypersensitivity reactions to banana, but the molecular basis of these putative cross-reactions is unknown.

OBJECTIVE

We wanted to examine whether proteins resembling hevein, a major NRL allergen, exist in banana and whether coexisting allergy to NRL and banana can be explained by IgE cross-reactivity to these proteins.

METHODS

Allergens in banana cross-reacting with hevein were identified by IgE immunoblot inhibition. The cross-reacting proteins were purified by reversed-phase chromatography and characterized by amino acid sequencing. Allergen cross-reactivity was further assessed by IgE ELISA, IgE ELISA inhibition, and skin prick testing.

RESULTS

In immunoblotting, 9 of 15 sera from patients allergic to NRL with IgE to hevein showed IgE binding to 32- and 33-kd banana proteins. These 2 protein bands were also targets to IgG from a hevein-immunized rabbit. IgE binding to both 32- and 33-kd protein bands was totally inhibited by hevein (10 ng/mL) in all 5 sera from patients allergic to NRL sera studied. N-terminal sequencing of the purified 32- and 33-kd proteins revealed 80% identity to the N-terminus of hevein. An internal peptide (19 amino acids) of the 33-kd protein gave over 90% identity to endochitinases of several plants. In ELISA all 15 sera from patients allergic to NRL had IgE to the purified 32-kd banana protein. In ELISA inhibition hevein (10 ng/mL) inhibited approximately 50% of IgE binding to the solid-phase 32-kd banana protein in a pool of sera from patients allergic to NRL.

CONCLUSION

These results suggest that the commonly occurring hypersensitivity to banana in patients allergic to NRL could be explained by cross-reacting IgE antibodies binding to epitopes in hevein and in a hevein-like domain of a previously undescribed endochitinase in banana.

IgE antibodies to prohevein, hevein, and rubber elongation factor in children with latex allergy

BACKGROUND

Prohevein (Hev b 6.01) and hevein (Hev b 6.02) have been shown to be major IgE-binding allergens in health care workers and other adult patients allergic to natural rubber latex (NRL). Rubber elongation factor (REF; Hev b 1) and the 23/27 kd NRL allergen (Hev b 3) are characteristic of children with latex allergy who have spina bifida and other children requiring multiple operations at an early age. In addition, there are children with latex allergy and no history of multiple operations in whom sensitizing allergens are not known.

OBJECTIVES

We studied IgE antibodies to NRL allergens in children with latex allergy who had not undergone surgery and compared the findings with those in children with latex allergy and a history of multiple operations.

METHODS

Sera from 30 children with latex allergy who had not undergone surgery, 12 children with latex allergy with a history of multiple operations, and 19 control children without evidence of NRL allergy were examined. Immunoblotting was used to study IgE binding to NRL proteins, and purified prohevein, hevein, and REF were used in ELISA to measure specific IgE antibodies.

RESULTS

In immunoblotting, sera from 21 (70%) children who had not undergone surgery and from 4 (33%) children with a history of multiple operations showed IgE binding to a 20-kd protein band (known to contain prohevein), and 9 (30%) and 8 (67%) sera, respectively, to a 14-kd protein band (known to contain REF). In ELISA, sera from 26 (86%) children who had not undergone surgery and from 7 (58%) children with a history of multiple operations had IgE antibodies to prohevein and 19 (63%) and 7 (58%) sera, respectively, to hevein. Eight (27%) sera from the children who had not undergone surgery had IgE antibodies to REF in contrast to 8 (67%) sera from children with a history of multiple operations.

CONCLUSIONS

The IgE antibody pattern differs between children with latex allergy who had not undergone surgery and those with a history of multiple operations. The major allergens in children with no history of surgery appear to be prohevein and hevein and not REF, a finding that agrees well with that reported for health care workers with allergy to latex.

Prediction of myocardial infarction in dyslipidemic men by elevated levels of immunoglobulin classes A, E, and G, but not M

BACKGROUND

Immune mechanisms have been suggested to play an important role in the development of coronary atherosclerosis and its thrombotic complications. We evaluated the predictive value of the levels of various serum immunoglobulin classes in middle-aged men at increased risk of myocardial infarction.

METHODS

Using nested case-control design and logistic regression analysis, we estimated the association between serum immunoglobulins and the risk of coronary end points (nonfatal or fatal myocardial infarction or sudden cardiac death) in dyslipidemic men (levels of non-high-density lipoprotein cholesterol >5.2 mmol/L [>201 mg/dL]) participating in the Helsinki Heart Study. The cases consisted of 135 subjects in whom a coronary end point occurred during the 5-year observation period of the study, and the controls were 135 subjects who did not suffer coronary end points during this period. Levels of IgA, IgE, IgG, and IgM were determined in serum samples collected at study entry.

RESULTS

Levels of IgA, IgE, and IgG, but not IgM, were significantly higher in cases than in controls. After adjustment for other risk factors, such as age, smoking, and blood pressure, the risk of coronary disease showed a significant relation to the levels of IgA, IgE, and IgG. The risk in the highest quartile of each distribution as compared with the lowest quartile was 2.2-fold for IgA (95% confidence interval, 1.0-4.5), 2.8-fold for IgE (1.3-5.9), and 2.8-fold for IgG (1.3-5.9). Hypertriglyceridemia and a low level of high-density lipoprotein cholesterol were associated with increased risk of a coronary end point only if the levels of IgA, IgE, or IgG were also elevated.

CONCLUSION

Elevated levels of IgA, IgE, and IgG are associated with myocardial infarction and cardiac death in men with dyslipidemia. The present data suggest that, for dyslipidemia to cause coronary atherothrombosis, an immune response reflected by elevated levels of these immunoglobulin classes is an important determinant.

Serum androgen-anabolic hormones and the risk of rheumatoid arthritis

OBJECTIVE

It has been hypothesised, mainly on the basis of indirect evidence, that low serum concentrations of androgen-anabolic hormones would play a causal part in the aetiology of rheumatoid arthritis (RA).

METHODS

A case-control study was nested with a Finnish cohort of 19,072 adults who had neither arthritis nor a history of it at the baseline examination during 1973-1977. Pre-illness serum specimens for the assay of testosterone and dehydroepiandrosterone sulphate (DHEAS) were available from 116 cases who had developed RA by late 1989. Three controls per each incident case were individually matched for sex, age, and municipality.

RESULTS

The mean testosterone concentration was 1.4 nmol/l in those 84 women who developed RA and 1.4 nmol/l in their controls; the corresponding figures for DHEAS were 5.2 mumol/l and 5.5 mumol/l, respectively. Mean testosterone concentration in the 32 male cases was 26.1 nmol/l and 26.4 nmol/l in their controls; the corresponding figures for DHEAS were 11.2 mumol/l and 10.1 mumol/l, respectively. Analysis by subgroups (rheumatoid factor positive and negative disease, pre-menopausal and postmenopausal women) and by hormone distributions showed no differences.

CONCLUSION

The findings are not in line with the contention that low concentrations of testosterone and DHEAS play a part in the aetiology of RA.

Purification of filaggrin from human epidermis and measurement of antifilaggrin autoantibodies in sera from patients with rheumatoid arthritis by an enzyme-linked immunosorbent assay

BACKGROUND

The so-called antikeratin antibody (AKA) and the antiperinuclear factor (APF) that recognize proteins related to human epidermal filaggrin belong to the most specific serological markers of rheumatoid arthritis (RA). However, assays for the detection of AKA and APF are currently based on immunofluorescence, a method that is subject to arbitrary interpretation and inadequate standardization of the substrates.

METHODS

Proteins extracted from human epidermis were separated by reversed-phase high-performance liquid chromatography (HPLC). Filaggrin-containing fractions, identified in immunoblotting by monoclonal antifilaggrin antibodies, were then subjected to gel filtration HPLC and, finally, to a second reversed-phase HPLC step. Tryptic digestion, amino acid sequencing and mass spectrometry were used to confirm the identity of the purified protein. Filaggrin was used as antigen in enzyme-linked immunosorbent assay (ELISA) to measure IgG class antifilaggrin antibodies.

RESULTS

The filaggrin preparation obtained gave a single band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, binding monoclonal antifilaggrin antibody in immunoblotting. Amino acid sequences of all 10 tryptic peptides analyzed were shown to originate from human filaggrin. Antifilaggrin antibody levels exceeded the 99th percentile level of 100 middle-aged blood donors in 26/55 (47%) RA sera. At a similar cutoff level 28/55 (51%) of the RA sera were positive in the AKA test. Of the 26 antifilaggrin-positive sera, 21 were also AKA-positive.

CONCLUSION

Human filaggrin can be purified by standard biochemical techniques, despite the heterogeneity of the protein, and used in ELISA for testing autoantibodies to filaggrin. The sensitivity of the assay equals that of the AKA test.

Antibodies to prothrombin crossreact with plasminogen in patients developing myocardial infarction

In a prospective study on healthy middle-aged men, high level of antibodies to prothrombin implied a risk of myocardial infarction. The possible mechanism(s) of these antibodies in coronary thrombosis are not known. Because prothrombin belongs to the kringle proteins and shares structural homology with a fibrinolytic kringle protein plasminogen, we studied whether antibodies to prothrombin crossreact with plasminogen. Sera from 17 healthy middle-aged men who later developed myocardial infarction were studied. Binding of antibodies to immobilized prothrombin (EIA) was inhibited by using soluble prothrombin, plasminogen and synthetic peptides of 20 amino acids from plasminogen kringle 5 (P304, P305) and from prothrombin kringle 2 (P302) as inhibitors. The peptides contained the conserved pentapeptide CRNPD of the kringle proteins. Soluble prothrombin inhibited up to 50% the binding of antibodies to immobilized prothrombin in all sera. Plasminogen inhibited binding in 9/17 (53%) sera (a decrease of at least 20%). P305 inhibited binding to prothrombin in 8/17 (47%), P304 in 4/17 (23%) and P302 in 6/17 (35%) sera. In structural analysis, presentation of the pentapeptide was conformationally different between the peptides. We conclude that crossreactive antibodies binding to prothrombin and plasminogen occur in sera of patients later developing myocardial infarction. The crossreactive epitope seems to be conformational and include the conserved pentapeptide of the kringle proteins. These antibodies may interfere with the fibrinolytic function of plasminogen and contribute to the development of myocardial infarction.

Measurement of natural rubber latex allergen levels in medical gloves by allergen-specific IgE-ELISA inhibition, RAST inhibition, and skin prick test

Exposure to natural rubber latex (NRL) medical gloves poses risks to patients sensitized to NRL and to users of protective gloves. Previous studies have shown that extractable allergen levels of the gloves vary widely. Since most of the available laboratory methods of NRL allergen measurement lack adequate validation, we wanted to evaluate the performance of a recently developed competitive IgE-ELISA-inhibition method in relation to the skin prick test (SPT) and RAST inhibition, as well as to extractable protein quantification and an immunochemical latex antigen assay (LEAP). Twenty samples of surgical (n = 14) and examination gloves (n = 6), covering > 90% of medical gloves marketed in Finland in 1994-5, were collected by the Finnish National Research and Development Centre for Welfare and Health, coded, extracted, and analyzed by the five methods. The IgE-ELISA inhibition correlated highly significantly with SPT (r = 0.94) and RAST inhibition (r = 0.96). Likewise, ELISA inhibition and RAST inhibition showed highly significant correlation (P = 0.96, P < 0.0001 in all three instances). Protein quantification by a modified Lowry method also correlated highly significantly with SPT (r = 0.80), RAST inhibition (r = 0.82), and ELISA inhibition (r = 0.81, P < 0.0001 in all three instances). Clearly weaker correlation, though statistically significant (r = 0.48, P = 0.03), was found between SPT and the LEAP assay. An NRL standard preparation was assigned an arbitrary content of 100,000 allergen units (AU) per ml. In relation to this standard, the NRL allergen level was considered low (< 10 AU/ml) in 11, moderate (10-100 AU/ml) in two, and high (> 100 AU/ml) in seven of the 20 glove brands analyzed. In conclusion, the results of a novel IgE-ELISA-inhibition method of measuring NRL allergen levels in medical gloves correlated highly significantly with those of SPT. The ELISA method was found to be sensitive, reproducible, technically easy, inexpensive, and suitable for the analysis of large numbers of NRL products. The results of extensive market surveys in 1994 and 1995, communicated to the medical community in Finland, appear to have had a clear effect in moving glove purchasing policies toward the use of low-allergen gloves.

Antibody to stratum corneum (antikeratin antibody) and antiperinuclear factor: markers for progressive rheumatoid arthritis

The purpose of this study was to examine the relationship between circulating antibodies to stratum corneum (AKA) and antiperinuclear factors (APF) on one hand, and the x-ray progression of joint damage in chronic poly/oligoarthritis on the other hand. The analysis involved 133 patients with either rheumatoid or nonspecific arthritis derived from a cohort of 442 patients with recent onset arthritis. The patients were followed up for eight years with regular clinical, laboratory, and radiological evaluations. Radiographic evidence of joint destruction was quantitated by a radiographic index based on the Larsen grading. AKA and APF were detected, either at entry or at follow-up, in 26 and 54 patients, respectively. Seventy-six of the 133 patients had developed erosions. All AKA-positive patients had a rheumatoid factor-positive erosive poly-arthritis. The presence of APF was also associated with a progressive arthritis although four APF-positive patients had a non-erosive disease. Neither AKA nor APF were able to distinguish a particularly severe form of progressive RA.

Natural rubber latex allergy in children who had not undergone surgery and children who had undergone multiple operations

BACKGROUND

Children with spina bifida and other children requiring multiple surgical procedures represent a well-known risk group for natural rubber latex allergy. Children not undergoing surgery can also be sensitized, but findings in this group of children with latex allergy have not been thoroughly examined.

OBJECTIVES

We sought to examine the frequency of latex allergy in a large group of children admitted for inhalant or food allergy testing for the purpose of collecting information on a series of children with latex allergy and comparing the symptoms and findings between those not undergoing surgery and those undergoing multiple operations.

METHODS

Children admitted to the allergy laboratory of Tampere University Hospital were screened by skin prick tests (SPTs) with latex glove extract. All children with allergy as determined by the screening or admitted because of suspected latex allergy were reexamined from 1995 to 1996. For a definite diagnosis of latex allergy, positive SPT, latex RAST, and latex glove use test results were required.

RESULTS

From 1992 to 1995, a total of 3269 children were skin prick tested with latex glove extract, and 55 (1.7%) had a positive response. On reexamination, 37 (1.1%) children had positive responses to SPTs, and 33 (1.0%) were confirmed to have latex allergy by means of RASTs and latex glove use tests. Since 1988, we have identified a total of 30 children with latex allergy who had not undergone surgery and 12 who underwent multiple operations. The clinical histories were similar in both groups; the mean ages at diagnosis were 5.7 and 8.1 years, and the frequency of atopy was 97% and 83%, respectively. Symptoms had occurred in 63% of the children who had not undergone surgery and in 75% of the children who underwent multiple operations. Contact urticaria was the most frequent symptom, and only one child had intraoperative anaphylaxis. Balloons, followed by gloves, were the most common latex products causing symptoms. The children with latex allergy who had not undergone surgery and those who underwent multiple operations showed no significant differences in SPT responses to commercial latex allergen extract or in specific IgE levels.

CONCLUSIONS

The prevalence of latex allergy among children admitted for inhalant or food allergy testing was 1%. Although multiple operations at an early age are a well-known risk factor for latex allergy, the majority of children with latex allergy identified at screening or admitted because of suspicion of latex allergy belonged to the group of children who had not undergone surgery. One third of all the children studied were free of symptoms, indicating that screening with SPTs can be a valuable tool for detecting occult latex allergy in children.

High antibody levels to prothrombin imply a risk of deep venous thrombosis and pulmonary embolism in middle-aged men--a nested case-control study

Antibodies against phospholipid-binding plasma proteins, such as beta2-glycoprotein I (beta2-GPI) and prothrombin, are associated with thromboembolic events in patients with systemic lupus erythematosus and also in subjects with no evident underlying diseases. We wanted to examine whether increased levels of antibodies to negatively-charged phospholipids (cardiolipin), to phospholipid-binding plasma proteins beta2-GPI and prothrombin and to oxidised low-density lipoprotein (LDL) were associated with risk of deep venous thrombosis or pulmonary embolism in subjects with no previous thrombosis. The antibodies were measured in stored serum samples from 265 cases of deep venous thrombosis of the lower extremity or pulmonary embolism occurring during a median follow-up of about 7 years and from 265 individually matched controls. The study subjects were middle-aged men participating in a cancer prevention trial of alpha-tocopherol and beta-carotene and the cases of thromboembolic events were identified from nationwide Hospital Discharge Register. The risk for thrombotic events was significantly increased only in relation to antiprothrombin antibodies. As adjusted for body mass index, number of daily cigarettes and history of chronic bronchitis, myocardial infarction and heart failure at baseline, the odds ratio per one unit of antibody was 6.56 (95% confidence interval 1.73-25.0). The seven highest individual optical density-unit values of antiprothrombin antibodies were all confined to subjects with thromboembolic episodes. In conclusion, the present nested case-control study showed that high autoantibody levels against prothrombin implied a risk of deep venous thrombosis and pulmonary embolism and could be involved in the development of the thrombotic processes.

Low-dose aspirin in prevention of miscarriage in women with unexplained or autoimmune related recurrent miscarriage: effect on prostacyclin and thromboxane A2 production

Early pregnancies in women with a history of recurrent spontaneous abortion (RSA) are accompanied by a deficiency in vasodilatory and anti-aggregatory prostacyclin (PGI2) and/or overproduction of its endogenous antagonist thromboxane A2 (TXA2). We evaluated the effect of a low-dose aspirin (LDA) on PGI2 and TXA2 production and on pregnancy outcome in RSA women with and without detectable anticardiolipin antibodies (ACA). Of 82 RSA women studied, 66 became pregnant, and of them, 33 (six with elevated and 27 with normal ACA concentrations) were randomized to receive LDA (50 mg/day) and 33 (six with elevated and 27 with normal ACA concentrations) to receive placebo (PLA) from a mean of 6.6 days after the missed period to delivery. Treatment with LDA inhibited platelet TXA2 production similarly in RSA women with and without detectable ACA and with continuing pregnancies (7.0 +/- 0.7 ng/ml, LDA group versus 254.5 +/- 37.8 ng/ml, PLA group, mean +/- SEM, P < 0.0001) or miscarrying pregnancies (13.8 +/- 3.8 ng/ml compared with 233.6 +/- 59.8 ng/ml, P < 0.0001 respectively). Furthermore, LDA decreased urinary excretion of the TXA2 metabolite (2,3-dinor-TXB2) both in pregnancies which went to term (6.1 +/- 0.6 ng/mmol creatinine, LDA group versus 19.3 +/- 3.0 ng/mmol creatinine, PLA group, P < 0.0001) or again ended in miscarriage (4.7 +/- 0.8 ng/mmol creatinine versus 17.3 +/- 4.4 ng/mmol creatinine, P < 0.0001 respectively), but did not affect the excretion of the prostacyclin metabolite (2,3-dinor-6-keto-PGF1alpha). Early pregnancy ultrasound examination revealed a living fetus in 58 women. Of these, seven in the LDA group (23.3%, four with elevated and three with normal ACA concentrations) and five in the PLA group (17.9%, two with elevated and three with normal ACA concentrations; not significant) experienced a miscarriage. All infants were healthy, and the frequency of growth retardation was similar in both groups (13.0%). One woman in the LDA group (4.3%) and three women receiving PLA (13.0%) developed pre-eclampsia (not significant). Therefore, although treatment with LDA caused a desirable biochemical effect, it did not improve pregnancy outcome in RSA women with or without detectable ACA.

Effect of ebastine on mosquito bites

Mosquito bites usually cause wealing and delayed bite papules. Cetirizine decreases wealing, bite papules and pruritus but the effect of other antihistamines on mosquito bites is unknown. We studied the effect of ebastine in 30 mosquito bite-sensitive adult subjects. Ebastine 10 mg or 20 mg and placebo were given for 4 days in a cross-over fashion. Aedes aegypti bites were given on forearms. The size of the bite lesions and pruritus (visual analogue score) were measured at 15 min, 2, 6, and 24 h after the bites. Twenty-five subjects were evaluable in the study. At 15 min ebastine decreased significantly the size of the bite lesion (p = 0.0017) and pruritus (p<0.0001). The effects of 10 mg and 20 mg of ebastine were similar. No significant effect was found at 2, 6 or 24 h, but when the measurements at all four time points were compiled the size of the bite lesion and pruritus score decreased significantly. Sedation occurred during ebastine treatment in 6 (21%) and during placebo treatment in 2 (7%) subjects. The present results show that prophylactically given ebastine is effective against immediate mosquito bite symptoms.

Serum immunoglobulins and the risk of rheumatoid arthritis

OBJECTIVE

Rheumatoid arthritis (RA) is associated with several autoantibodies that can precede the clinical disease. The immunoglobulin concentrations in serum samples before illness were studied to learn more about the immunological process before RA.

METHODS

A case-control study was nested within a Finnish cohort of 19,072 adults who had neither arthritis nor a history of it at the baseline examination during 1973-1977. By late 1989, 124 had developed RA, of which 89 were positive for rheumatoid factor (RF). Three controls per each incident case were individually matched for sex, age, and municipality. The concentrations of IgG, IgA, and IgM were measured from stored serum samples.

RESULTS

Serum IgG before illness was found to be directly proportional to the risk of RF positive RA, and a non-linear association was present between serum IgA and the risk of RF positive RA. These associations were constant between men and women and other subgroups of the study population and not confounded by serum orosomucoid concentration, level of education, smoking, alcohol intake or body mass index. As adjusted for these factors, the odds ratios (95% confidence intervals) of RF positive RA in the lowest, mid, and highest tertiles of IgG distribution were 1.00, 1.55 (0.81, 2.97), and 2.22 (1.16, 4.26), and in the tertiles of IgA 1.00, 2.23 (1.14, 4.36), and 1.78 (0.89, 3.57), respectively. The associations persisted throughout the entire observation period but were most distinct when the period to the onset of clinical RA was > or = 10 years. IgM carried no predictive significance. None of the serum immunoglobulins predicted the development of RF negative RA.

CONCLUSIONS

Increased IgG levels may reflect some, at present unknown process in the early events leading to the development of RA, typically occurring > or = 10 years before the onset of clinical disease.

Detection of mosquito saliva-specific IgE antibodies by capture ELISA

We developed an IgE-capture ELISA and measured mosquito saliva-specific IgE antibodies in 27 children sensitive to mosquito bites. Children with large 15-min bite wheals had significantly higher (P < 0.0005) mosquito saliva-specific IgE levels than children with small wheals. In the latter group, the saliva-specific IgE level was significantly higher (P = 0.031) than the levels of six infants never exposed to mosquitoes. A positive correlation (r = 0.65; P = 0.0002) was found between the size of the 15-min wheal and the mosquito saliva-specific IgE antibody levels. These results further support the role of mosquito saliva-specific IgE antibodies in the pathogenesis of mosquito-bite whealing. Compared to immunoblotting, IgE-capture ELISA provides a quantitative method to measure mosquito saliva-specific IgE antibodies.

Characterization of Aedes communis, Aedes aegypti and Anopheles stephensi mosquito saliva antigens by immunoblotting

BACKGROUND

Mosquito bites cause immediate wheals and delayed bite papules in sensitized subjects having saliva-specific IgE and IgG4 antibodies. At present, mosquito saliva antigens are not well characterized.

METHODS

To identify immunogenic proteins in mosquito saliva and study their cross-reactivity we immunized mice with Aedes communis, Aedes aegypti and Anopheles stephensi bites. Immune sera were used in immunoblotting and immunoblot inhibition experiments.

RESULTS

The main A. communis saliva antigens were 22-, 30-, and 36-kD, A. aegypti saliva antigens 31-, 36-, 46- and 64- to 66-kD, and A. stephensi saliva antigen 46-kD proteins. Most of the saliva antigens appeared to be species-specific and only weak cross-reactivity was observed with heterologous immune sera. Distinct cross-reactivity was observed only between saliva proteins of A. communis and Aedes punctor, two taxonomically closely related species. Human IgE and IgG4 antibodies from mosquito-bite-sensitive children bound to the same saliva proteins as antibodies from the immunized animals.

CONCLUSIONS

This study disclosed several immunogenic proteins in Aedes and Anopheles mosquito saliva and suggests that these proteins can also be allergenic in man.

Latex allergy diagnosis: in vivo and in vitro standardization of a natural rubber latex extract

For the diagnosis of IgE-mediated (immediate) hypersensitivity to natural rubber latex (NRL), skin prick testing with extracts of latex gloves has been widely used, but such extracts are difficult to standardize. The present study aimed to produce on an industrial scale an NRL extract from freshly collected NRL and to evaluate, calibrate, and standardize the extract by both in vivo and in vitro testing. The source material, latex of the rubber tree, Hevea brasiliensis (clone RRIM 600), was frozen immediately after collection in Malaysia and shipped in dry ice to Stallergènes SA, France. Protein and allergen profiles were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), immunoblotting, isoelectric focusing (IEF), crossed immunoelectrophoresis (CIE), and crossed radioimmunoelectrophoresis (CRIE). Allergen quantification was effected by RAST inhibition. The capacity of the preparation to elicit immediate hypersensitivity reactions in vivo was measured by skin prick testing in 46 latex-allergic patients and 76 nonallergic control subjects. SDS-PAGE and immunoblot profiles of the extract and an NRL standard (E8) provided by the US Food and Drug Administration were almost identical, disclosing several distinct IgE-binding proteins with apparent molecular weights of 14, 20, 27, 30, and 45 kDa, conforming to reported molecular weights of several significant NRL allergens. An arbitrary index of reactivity (IR) of 100 was assigned to the extract at 1:200 dilution (w/v), having a protein content of 22 micrograms/ml. Skin prick testing of latex-allergic patients and controls using the extract at 100 IR revealed 93% sensitivity, 100% specificity, 100% negative predictive value, and 96% positive predictive value. In conclusion, a skin prick test reagent for diagnosis of type I NRL allergy was successfully standardized. The reagent was demonstrated to contain most, if not all, of the currently known clinically significant NRL allergens, and it showed high sensitivity and specificity.

Antibodies to beta 2-glycoprotein I and prothrombin in habitual abortion

OBJECTIVE

To determine the occurrence of antibodies to beta 2-glycoprotein I (beta 2-GP-I) and prothrombin in women with histories of habitual abortions when pregnant and nonpregnant.

DESIGN

Antibodies to beta 2-GP-I and prothrombin were measured by ELISA using irradiated polystyrene plates in 43 women with habitual abortions and 22 healthy controls.

SETTING

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

PATIENT(S)

Twenty-two women of the habitual abortion patients had never delivered (primary aborters) and 21 had delivered at least one living child before miscarriage (secondary aborters).

INTERVENTION(S)

Venous blood samples were collected before and during pregnancy.

MAIN OUTCOME MEASURE(S)

Immunoglobulin G class antibodies to beta 2-GP-I and prothrombin.

RESULT(S)

The secondary aborters showed higher levels of antibodies to prothrombin than the primary aborters when both pregnant and nonpregnant and also showed higher levels of antiprothrombin antibodies than the controls when pregnant. No such differences were found in levels of antibodies to beta 2-GP-I. The habitual abortion patients showed a tendency toward higher levels of these autoantibodies when pregnant than when nonpregnant. Gestational diabetes was more common among the antibody-positive habitual abortion patients than among the antibody-negative patients.

CONCLUSION(S)

Increased levels of antiprothrombin antibodies were associated with secondary abortions. Elevated levels of antibodies to beta 2-GP-I and prothrombin often were found in habitual abortion patients with gestational diabetes.