T. G. Merrett

Effects of anti-mite measures on children with mite-sensitive asthma: a controlled trial.

Mite counts and tests for mite antigen were performed on samples of dust taken from the bedding of 53 children with mite-sensitive asthma. The samples from damp houses and the beds or enuretic children had markedly more mites and mite-antigen than those from dry houses. although the predominant species was usually Dermatophagoides pteronyssinus, some of the beds in the damp houses were heavily infested with another pyroglyphid mite Euroglyphus maynei, so that this was the species found in the greatest numbers. D pteronyssinus antigen was found to be correlated broadly with the total mite count, but more antigen was present for a given number of mites in the mattresses than in the blankets. The children were randomly allocated into two groups, one of which carried out rigorous anti-mite measures. The amounts of dust and mite antigen were reduced, though not the numbers of mites. Peak flow readings were monitored in the two groups for eight weeks and a final assessment made by a paediatrician who was unaware of the allocation of each patient in the trial. No significant differences emerged in the progress of the two groups, both tending to improve. Measures designed to remove mites from bedding do not greatly benefit the majority of children with mite-sensitive asthma.

Immunologic studies in allergen-induced late-phase asthmatic reactions

We have measured plasma histamine, serum neutrophil chemotactic activity (NCA) and complement (C3 and C4) over a 24-hour period in patients experiencing either early- and late-phase (dual) or single early asthmatic reactions to inhaled allergens. There was a significant biphasic elevation in plasma histamine, which paralleled the fall in forced expiratory volume in 1 sec in 10 patients with dual responses, whereas in seven subjects with single early reactions, only a single early increase in histamine concentrations was observed. In general, in the individual subjects, the changes in plasma histamine paralleled both the elevations in serum NCA and the decreases in forced expiratory volume in 1 sec. By gel filtration on Sephacryl S-400, anion exchange chromatography on DEAE Sephacel, and chromatofocusing with Polybuffer Exchanger 94, the major NCA of both the early and the late reactions was associated with proteins having an estimated molecular size of 600,000 daltons, an elution from DEAE Sephacel at 0.15M to 0.30M of NaCl (pH 8.1), and a pI of approximately 6.5. There were no appreciable changes in serum C3 and C4 up to 24 hr after challenge in subjects with late-phase responses. The patterns of asthmatic response were not related to either the total or allergen-specific serum IgE or IgG4 concentrations. These results support the view that mediators of hypersensitivity participate in late-phase as well as early asthmatic reactions.

The development of allergy in high-risk children

Background It is uncertain as to what extent the development of allergic disease in childhood is predictable during early infancy. A number of environmental factors have been suspected of increasing the risk of acquiring allergy, but the evidence is conflicting.

Environmental factors and symptoms in infants at high risk of allergy.

STUDY OBJECTIVE: To identify environmental determinants of six symptoms associated with allergic disease in infancy. DESIGN: Infants were participants in a prospective randomised controlled trial of feeding practices in families with a history of atopy. SETTING: Infants were recruited in two maternity hospitals in S Wales and followed up in the community for 1 year. PARTICIPANTS: Mothers of 519 infants agreed to participate, but 36 were excluded (mainly for moving home or failing to attend for follow-up), leaving 483 in the study (253 male, 230 female). Infants were followed up and examined for evidence of allergic disease at 3, 6, and 12 months. MEASUREMENTS AND MAIN RESULTS: At each examination, mothers were questioned about episodes of illness in the infant, and the data presented relate to (reported and observed) eczema and nasal discharge, and (reported) wheeze, prolonged colds, diarrhoea and vomiting. Mothers kept a diary with details of feeding for the first 6 months. All homes were visited by a nurse who took samples of dust for dust mite antigen analysis. Extensive socio-demographic data were collected. None of the factors studied showed a convincing relationship with eczema. In a multiple logistic regression analysis breast feeding appeared to protect against wheeze, nasal discharge, colds, vomiting and diarrhoea. Having more siblings increased the likelihood of prolonged colds, and (together with overcrowding) of wheeze and nasal discharge. Maternal smoking and low social class were associated with wheeze, and house dust antigen with prolonged colds. Respiratory symptoms were associated with some aspects of housing but these could not be distinguished clearly from other social factors. Babies born in Autumn were at increased risk of wheeze, vomiting and diarrhoea. CONCLUSIONS: Environmental factors play an important part in determining risk of symptoms in potentially atopic babies. These factors are in principle open to manipulation.

A community survey of asthmatic characteristics.

A survey was undertaken among adults aged 20-44 years in a South Wales town. Persons with a history of wheezing with breathlessness and in the absence of a cold were identified by postal questionnaires and seen at a clinic, together with a sample of subjects without these symptoms. The response rates for the first and second stages of the survey were 99.6% and 91.0% respectively, and 574 subjects were ultimately seen. Asthmatic patients (those receiving treatment within the previous year) had some airways obstruction at rest, which increased after exercise. They also had strong allergic tendencies, as shown by personal and family history, skin tests, and serum IgE levels. The ex-asthmatics (those not receiving treatment within the previous year) showed these tendencies to a lesser extent. A larger group gave a history of wheezing but stated that they had never had asthma; in their response to exercise and allergic traits they resembled the control group rather than the asthmatics, and appeared to have the features of chronic bronchitis. Asthma and chronic bronchitis would therefore seem to be distinct entities within the population studied.

Food intolerance: a community survey.

1. A questionnaire inquiring about food intolerance was sent to a random sample of the electorate in a small South Wales town. Replies were received from 170 men and 305 women, the response rates being 87 and 93% respectively. 2. Adverse effects of some food were reported by 19% of men and 26% of women, or 14 and 18% respectively if minor digestive symptoms are excluded. Certain foods were thought to cause non-abdominal symptoms by 4% of men and 10% of women, and vomiting, diarrhoea or abdominal pain by 11% of men and 10% of women. 3. Plasma IgE was measured in a random subset of ninety-nine women and found to be significantly lower in those with major symptoms than in the rest. This suggests that allergy is probably not a common cause of food intolerance.

A community survey of IgG4 antibody levels.

Precise and specific radioimmunoassays have been developed to quantify IgG4 and IgG4 antibodies. A community survey has demonstrated that men have significantly higher total serum lgG4 levels than women: geometric mean values of 0.581 mg/ml versus 0.302 mg/ml. This sex difference was extended to total IgE values. Circulating levels of IgG4 antibodies against foods, especially egg‐and milk, were normally higher than those against the three most common U.K. inhalant allergens–grass pollen, house dust mite and cat epithelium,

Circulating IgE levels in the over-seventies

In a normal population aged over 70 years the geometric mean IgE value of 30.6 u/ml was not significantly different from that obtained previously in a similar epidemiological survey of a population aged 20–44 years. However, in the older population we have noted a significant sex difference–38.6 u/ml for males against 27.2 u/ml for females–which was only apparent in the atopic subjects of the younger population. There have been some other reports that IgE levels decrease with age, and possible reasons for these differences with our own results are discussed.

Is the determination of cord blood total IgE levels any value in the prediction of atopic disease

Sirs, two articles have appeared in recent issues oi Clinical and Experimental Allergy referring to this topic [1,2]. We are glad that the data presented in both confirm our original report that there is no threshold value of total IgE in cord blood that can be used to predict atopy [3], but disappointed that the authors failed to cite the original study. This oversight seems also to have afflicted your reviewers. In the mid-1980s it was taken for granted that cord blood total IgE levels were of value [4-7] and our careful study was the only one to go against the tide of opinion. In at least one European country the cost of laboratory testing was, and still is, reimbursable on that basis.

Circulating levels of beta 2-microglobulin in the over 70s

The median serum beta 2-microglobulin value for a population aged over 70 years was 2.30 mg/l. This value increased significantly with age in both men and women--there were no sex differences.