Judith McCullough

The prevalence of anti-latex IgE antibodies in 1000 volunteer blood donors

BACKGROUNDnLatex allergy has been recognized as a medical problem with increasing frequency since the mid 1980s. Although certain groups of individuals, such as health care workers, have been recognized as having increased risk for latex allergy, little is known about the prevalence of latex allergy in the general population.nnnMETHODSnTo estimate the prevalence of latex allergy among healthy adults, we measured anti-latex IgE antibodies in residual serum samples from 1000 volunteer Red Cross blood donors. The 1000 samples were from a sample of blood units collected from workplace mobile sites throughout Southeastern Michigan. Samples collected from mobile sites operating at health care institutions were excluded to minimize sampling of health care workers. Anti-latex IgE antibodies were measured by using the AlaSTAT assay (Diagnostic Products Corp., Los Angeles, Calif.) according to the manufacturers directions. Samples with anti-latex IgE concentrations of 0.35 IU/ml or greater were classified as positive and samples with IgE concentrations of 1.50 IU/ml or greater were classified as strongly positive. All positive samples were assayed a second time to confirm the result. All positive samples were also measured with the CAP assay (Pharmacia Diagnostics, Dublin, Ohio).nnnRESULTSnThe samples tested were from donors with a mean age of 37.8 years, and 47% were women. Sixty-four (6.4%, 95% confidence interval = 4.9-8.1%) of the samples were confirmed as repeatedly positive for anti-latex IgE, and 23 of the 64 positive samples were strongly positive (2.3% of the 1000). Sixty-one percent of the samples positive as determined by the AlaSTAT assay were also positive as determined by the CAP assay. Samples from male donors were more likely to be positive than those from female donors (8.7% vs 4.1%, p = 0.003). Prevalence of positive samples was not related to age or race.nnnCONCLUSIONSnWe conclude that the prevalence of detectable anti-latex IgE antibodies, in a large and relatively unselected adult population, is higher than previous estimates have suggested. Although the clinical significance of these observations needs further evaluation, the data suggest that latex allergy is not confined to individuals in previously recognized high-risk groups.

Watermelon and ragweed share allergens.

A biotin-avidin amplified ELISA was used to measure antigen-specific IgE for ragweed, representative members of the gourd family (watermelon, cantaloupe, honeydew melon, zucchini, and cucumber), and banana in the sera of 192 allergic patients, each with an IgE greater than or equal to 180 microns/ml. Sixty-three percent (120/192) of the sera contained antiragweed IgE, and of these patients, 28% to 50% contained IgE specific for any single gourd family member. In contrast, no greater than 11% of the sera positive for a given gourd or banana were negative for ragweed. Correlations between ragweed and gourd-specific IgE levels were significant (p less than 0.001), and correlation coefficients between any two gourds exceeded 0.79. In an ELISA system, the extracts of watermelon and ragweed inhibited each other in a dose-dependent manner; the resulting nonparallel inhibition curves indicate that some, but not all, of the allergens in the two extracts are cross-reactive. Isoelectric focusing of watermelon and ragweed extracts in narrow range gel (pH 4 to 6) followed by immunoblotting demonstrated six watermelon allergen bands with isoelectric points identical to those of ragweed allergens. Several remaining bands in the two extracts had differing isoelectric points, however. Six of 26 patients interviewed with watermelon-specific IgE reported developing oropharyngeal symptoms (itching and/or swelling of the lips, tongue, or throat) after ingesting at least one of the study foods, whereas only one of 25 patients interviewed without detectable watermelon-specific IgE reported similar symptoms (p = 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Anaphylaxis after ingestion of beignets contaminated with Dermatophagoides farinae

A 48-year-old man was evaluated for anaphylaxis associated with ingestion of beignets prepared from a commercial mix. Microscopic examination of the patients beignet mix revealed live Dermatophagoides farinae. Another unopened box from the same source was not infested. Skin test results to aeroallergens and foods, including all beignet mix ingredients, were positive only to D. farinae and D. pteronyssinus extracts. Skin prick test results to an infested mix extract (1:5 wt/vol) were also positive, but no reaction was observed with noninfested mix extract. ELISA inhibition studies demonstrated significant inhibition of the patients serum binding to D. farinae strips by infected mix extract. Parallel inhibition curves were produced by the infested mix extract and a commercial D. farinae extract. Noninfested mix extract showed no inhibition. RAST analysis with beignet mix discs showed significant binding of the patients serum IgE to infested mix discs but not to noninfested mix discs. RAST inhibition studies revealed more than 86% inhibition of binding of the patients IgE to infested mix discs by infested mix extract and D. farinae extract. No inhibition was observed with noninfested mix or 5% fetal calf serum-phosphate-buffered saline. We conclude that the allergen to which the patient reacted was most likely D. farinae and that ingestion of D. farinae may cause anaphylaxis in sensitive persons.

Passive exposure to cigarette smoke does not increase allergic sensitization in children

The purpose of this study was to learn whether children passively exposed to parental cigarette smoke would be more frequently sensitized to common allergens or would have higher concentrations of allergen-specific IgE. To evaluate this question, we studied two groups of children aged 2 to 17 years. The first group consisted of 100 children selected from a general pediatric group practice. These children were being observed for well-child care, and the only selection criteria were the need for a venous blood sample for a reason unrelated to the study. The second group of 91 patients were consecutively referred, from the same pediatric group, for allergy evaluation because of respiratory tract symptoms. Parental smoking histories were obtained, and total serum IgE, IgD, and IgE specific for cat, dog, mite, ragweed, grass, and cockroach were measured by ELISA. Children of smoking mothers had significantly greater IgD concentrations (p = 0.03) and were more likely to be referred for allergy evaluation (p = 0.0001), but these children did not have increased concentrations of total or allergen-specific IgE. Exposed children were not more likely to be serologically sensitive to any of the allergens tested. We conclude that children passively exposed to cigarette smoke do not produce more IgE to common allergens nor are they more likely to produce IgE to any particular allergen.

Antibody responses in watermelon sensitivity

Watermelon-specific IgE (WM-IgE) appears to mediate the oropharyngeal symptoms after watermelon ingestion. However, less than one fourth of watermelon-sensitive individuals (i.e., those with detectable WM-IgE) develop such symptoms after watermelon ingestion. In an attempt to separate symptomatic from asymptomatic persons, we measured watermelon-specific-IgE and IgG4 concentrations in the sera of 29 watermelon-sensitive patients, 6 of whom were symptomatic. Although the mean WM-IgE level of the symptomatic group exceeded that of the asymptomatic group (p = 0.04), individual WM-IgE values failed to distinguish symptomatic from asymptomatic persons. No differences in WM-IgG4 levels between the two groups could be found. Watermelon extract proteins were separated by isoelectric focusing and blotted to nitrocellulose membranes. The membranes were reacted with the individual sera of 14 watermelon-sensitive patients and then stained for IgE, IgG1, and IgG4 binding. Great variations in IgE, IgG1, and IgG4 binding patterns were found, but no subtype restrictions were discovered. Although the pattern of IgE-stained bands in the absence of corresponding IgG1-stained bands was seen more frequently in symptomatic individuals, immunoblot patterns failed to separate symptomatic from asymptomatic persons. We conclude that the pattern of IgE, IgG1, and IgG4 responses to separated watermelon allergens was not predictive of clinical symptoms in a group of watermelon-sensitive patients.

An improved technique for separating rosetted from non-rosetted lymphocytes

An improved technique for separating rosetted from non-rosetted lymphocytes is described. The major advantage of this new technique is the elimination of the need to mechanically resuspend the cell pellet resulting from the rosette formation step before using a density gradient to separate the rosetted from the non-rosetted cells. Instead the rosette containing cell pellet is directly overlayed with Percoll at a density of 1.078 g/ml and during a subsequent centrifugation the non-rosetted cells float to the surface of the Percoll while the rosetted cells remain in the cell pellet. The utility of this technique is illustrated by separating human T lymphocytes forming rosettes with neuraminidase treated sheep erythrocytes (En) from other mononuclear cells obtained by Ficoll-Hypaque separation of whole blood. Using several markers the resulting T cells were contaminated with less than 0.3% monocytes and 2% B cells. The non-T cell population contained less than 3% T cells. This method offers a rapid and easily reproducible means for obtaining highly purified cell populations.

Immunologic Evaluation of Nasal Polyps

Forty-seven patients undergoing nasal polypectomy and 27 adult tonsillectomy patients were studied regarding history of allergy, duration of symptoms, and previous polypectomies. At surgery, samples of serum, tissues, and nasal washes were obtained for evaluation of total and allergen-specific IgE. Serum IgE levels were not significantly higher in polypectomy patients. The IgE/mg of protein was significantly greater in polyp than tonsil tissue. Allergen-specific IgE levels did not differ in polyp and tonsil patients, nor was bacterial specific IgE detected in polyp patients. Allergen-specific IgG4 levels and the ratios of specific IgG4 to specific IgE did not differ between the patient groups.