Skin test reactivity in infancy

Skin tests represent a major tool in the diagnosis of reaginic allergy; however, their interpretation does not appear to be without difficulty in children under the age of 3 yr. Seventy-eight infants from birth to 24 mo were prick tested and compared with 30 nonallergic adult subjects. Skin tests were performed without bleeding by use of two strengths of histamine hydrochloride (1 and 10 mg/ml), a mast cell degranulating agent (codeine phosphate, 50 mg/ml), and allergenic extracts. Negative control solution elicited a small wheal (less than 1.5 mm) in two infants who were excluded from further results. A clear and significant (p less than 0.001) hyporeactivity to both histamine and codeine phosphate was observed in infancy, especially before the age of 6 mo. Six infants were allergic and presented positive prick tests to either food or inhalant allergens. These tests were confirmed by serum specific IgE and a suggestive clinical history. The size of the allergen-induced prick test wheal ranged from 2 to 5 mm in diameter, suggesting that prick test wheals may be smaller in infants. This study confirms that prick tests can be performed and interpreted without difficulty in infants, keeping in mind the small wheal size induced by both positive control solutions and allergen-induced prick tests.     

Skin reactivity to purified pollen allergens in highly ragweed-sensitive individuals

Five hundred twenty-five atopic patients were skin tested over a 12-mo period to several crude allergens with a puncture skin-testing technique utilizing a bifurcated needle originally developed for smallpox immunization. Of these, 122 were highly allergic to short ragweed pollen and were subsequently tested with a series of purified grass and ragweed allergens. Data of their skin reactivity to these allergens is presented, and the phenomenon that each patient has a unique “allergic fingerprint” to purified pollen allergens is shown. The puncture technique showed good correlation with quantitative intradermal skin titration and offered a definite advantage, because many allergens could be rapidly and accurately assayed with good patient compliance.     

Insect venom allergy: a prospective case study showing lack of correlation between immunologic reactivity and clinical sensitivity

This case report demonstrates the lack of correlation between clinical sensitivity to insect venoms and immunologic reactivity as indicated by the presence of venom-specific IgE. A 20-yr-old venom collector was monitored over a 3-yr period with measurements of venom-specific IgE (skin test and RAST) and venom-specific IgG. In the first year of venom collection, multiple stings were tolerated with no reaction. In the second season, she had an anaphylactic reaction after a yellow jacket sting. Subsequently, there was a rising titer of serum yellow jacket and bee venom-specific IgE and positive skin-test reactions. In the third season, yellow jacket, hornet, and bee venom skin tests remained positive and serum IgE antibody titers remained elevated. Stings from all three insects were tolerated with no reaction. Throughout the 3-yr course, serum venom-specific IgG remained low and unchanged. The factors other than IgE-modulating clinical anaphylaxis, perhaps responsible for this clinical and immunologic dichotomy, are unknown. These observations add a further complication to the choice of patients for venom immunotherapy.     

Distribution of IgE in a community population sample: correlations with age,sex, and allergen skin test reactivity

The distribution of total serum IgE determined by the paper radioimmunosorbent test (PRIST) is examined in a large random stratified community population. Prior to logarithmic conversion the distribution of this immunoglobulin is not normal, with almost 40% of values below 20 lU/ml. A normal distribution occurs following such conversion, with a geometric mean value of 32.1 lU/ml. Both age and sex, in addition to atopic status, relate to IgE level. In both sexes highest levels occur among 6- to 14-year-olds, and males have higher levels than females at any given age. Women over age 75 yr have the lowest levels (geometric mean 9.2 lU/ml). Subjects with positive skin test results have several times the concentration of IgE as their nonatopic counterparts.     

HLA family studies and multiple sclerosis: A common gene,dominantly expressed

All available Australian families with more than one member suffering from multiple sclerosis (MS) were HLA typed. As with all other individual published studies, convincing evidence for linkage between the HLA system and disease was not obtained. An analysis of 100 published affected sib-pairs and 17 cousin-pairs, however, established the existence of an HLA-linked disease susceptibility gene for MS, which is likely to be dominantly expressed. Dominance was also supported by the finding of only three HLA-DR2 (Dw2) homozygous individuals out of 60 unrelated patients which enabled rejection of a recessive gene hypothesis (p < 0.02). Analysis of the sib-pair data strongly suggested that this MS gene is not rare in the normal population and may be as common as DR2.     

Efficacy and specificity of immunotherapy with laboratory animal allergen extracts

The clinical and immunologic response to immunotherapy with laboratory animal allergens was evaluated. There were 23 patients; 11 had received immunotherapy with 12 different extracts (five mouse, six rat, one rabbit), and 12 were matched untreated patients. As a group, nine of 23 had seasonal hay fever. Among the treated patients nine of 11 subjectively improved with immunotherapy. Blocking antibody titers were determined by serum inhibition of allergen-induced histamine release. Treated patients had mean blocking antibody levels of G₃₀ = 59.3 ± 38.7. In the untreated patients the antibody level was low (G₃₀ = 4.6 ± 3.6). The difference between the two groups was highly significant (t test p < 0.001). The blocking antibody level correlates with both the final weekly allergen dose and also the cumulative allergen dose received during immunotherapy. When pretreatment sera were available a temporal rise in blocking antibody was demonstrated during immunotherapy. In patients allergic to several laboratory animals and treated with one allergen, the blocking antibody response was predominantly specific to the allergen used in immunotherapy. This indicates a lack of cross-reactivity in the IgG response to the major animal allergens. When immunotherapy was discontinued in four patients there was a dramatic decrease in the blocking titer, and after 24 mo the levels were the same as those of untreated patients.     

Duration and specificity of sodium cromolyn on allergen inhalation challenges in asthmatics

Serum IgE levels are an important risk factor in allergic disease resulting from immediate-type hypersensitivity. IgE levels of middle-aged male monozygous twins (54 pairs) and dizygous twins (39 pairs) were measured and a significant genetic effect on IgE levels was observed (H = 0.592). A significant genetic effect was also noted in twin children (H = 0.789). The statistical relationship between IgE levels and atopic disease, as well as aspects of the methods of analysis of twin data, is discussed.     

A controlled study of the effect of corticosteroids on immediate skin test reactivity

Limited uncontrolled studies in the past have yielded conflicting results as to the ability of corticosteroids to suppress the immediate wheal-and-flare test. This double-blind controlled study, using 15 atopic volunteers, demonstrated that a one-week course of steroids exerted no significant effect, compared to placebo, on reactivity to ragweed wheal size and the threshold dilution measurements. Reactivity to compound 48–80 and histamine was also unaffected. In vivo effects of the steroid in these subjects was demonstrated by significant eosinopenia.     

Nonspecific bronchial reactivity in occupational asthma

The provocative concentration (PC₂₀ mg/ml) of methacholine required to produce a fall in the baseline FEV₁ by 20% was determined in 86 patients with occupational asthma due to exposure to western red cedar, California redwood, grain dust, or isocyanates. Fifty-seven patients were assessed at the time of diagnosis when they were symptomatic. Twenty-nine patients were studied after they had been removed from exposure for a period from 2 mo to 4 yr and were asymptomatic. Nine of the 57 patients with symptomatic asthma had repeat methacholine inhalation tests after removal from exposure. The results were compared with 33 normal healthy subjects, 30 patients with nonoccupational asthma, and 17 patients with nonindustrial chronic bronchitis. Patients with symptomatic occupational asthma had marked increase in bronchial reactivity similar to those with nonoccupational asthma. The degree of hyperreactivity decreased after removal from exposure and increased following re-exposure to the offending agents. There was little overlap in the range of PC₂₀ in the asthmatic compared with the nonasthmatic groups. These findings suggest nonspecific bronchial hyperreactivity is likely to be the consequence rather than the predisposing factor in occupational asthma. Methacholine inhalation test is a simple, safe, and useful procedure in the initial assessment of patients suspected to have occupational asthma before institution of time-consuming specific bronchial provocation test.     

Diagnosis of food allergy by the radioallergosorbent test

The radioallergosorbent test (RAST) was positive in 52.5% of 200 sera representing 200 food hypersensitivities from 108 patients with a history of definite immediate-type reactions to foods. Corresponding prick test was performed for 170 of the sera. The latter test was positive in 70%, the RAST was positive in 52%, and either prick test or RAST was positive in 74%. It is concluded that the RAST is positive less frequently than the prick test in the diagnosis of immediate-type food allergy in clinically sensitive patients, but that the performance of both tests increases slightly the possibility of confirming the diagnosis. However, the RAST is useful for further evaluating positive prick tests with foods that do not correlate with clinical hypersensitivity.     

Reproducibility of allergy epicutaneous test techniques

Three commonly used epicutaneous allergy skin test techniques, pinprick, chalazion knife, and Berkeley scarifier, were studied for size of response and reproducibility in the top, middle, and bottom regions of the back. All methods showed large variability, which was strongly influenced by the region of the back selected and the size of the wheal and flare reaction. Greater reproducibility was found with the larger skin test responses using the pinprick and scarifier techniques in the middle region of the back. The flare reaction was slightly less variable than the wheal response. Reproducibility and reaction size did not change significantly during the 4 week study period.     

Effect of a β-adrenergic agonist,fenoterol, on nasal sensitivity to allergen

Fenoterol hydrobromide, 1 mg/ml, was given by nasal spray in doses between 204 and 576 μg in an attempt to reduce nasal sensitivity to Lolium perenne allergen in a nasal provocation test during a 2-hr period following the drug. In a randomized double-blind comparison between fenoterol and placebo in 11 patients, reduction of nasal sensitivity by fenoterol was small but significant in a one-tailed test (p = 0.03). In the 15 min following the fenoterol spray the increase in the average nasal airway resistance (NAR) was significantly higher than the increase in NAR after placebo (p = 0.026), suggesting that fenoterol may also act as a vasodilator in the nose. This effect is consistent with findings by other investigators who showed that isoproterenol also increased nasal airways resistance.     

The natural history of food sensitivity

The natural history of food sensitivity has long been the subject of anecdotes about children “outgrowing” their problem, but prospective systematic studies are not easily found that document these opinions. Children who had had adverse reactions to foods during double-blind food challenges 1 to 7 yr prior to this study were evaluated. In children over 3 yr of age, 19% of the previously positive food challenges were negative at the time of the follow-up; in children 3 yr of age or younger, 44% of the food challenges that had been positive were negative. The data collected thus far suggest that children who have their food sensitivity diagnosed at older ages tend not to outgrow the problem. Skin testing was performed over a period of years on some of the subjects, and skin sensitization was found to be markedly persistent, even in subjects who could consume the sensitizing food without symptoms.