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IgG antibody against avian antigens was measured by quantitative radioimmunoassay in serum samples obtained regularly from twenty pigeon fanciers over a 1-year period. A seasonal variation was seen in nine antibody-positive subjects; eight of whom had symptoms of pigeon breeder's disease (PBD), and a clear peak of antibody production occurred during late summer, corresponding with the period of maximum avian contact in the sporting season. All subjects with insignificant specific IgG levels were asymptomatic and displayed minimal changes throughout the year despite a similar exposure pattern to antigen for all individuals. Raised total IgG was a feature of six symptomatic subjects, two of whom had raised total IgA. Three of these six subjects had maximum hypergamma-globulinaemia coinciding with peak specific-antibody levels, but in general the total immunoglobulin levels tended to remain high throughout the year with only marginal fluctuations. The total immunoglobulin levels in the other individuals were within normal limits and displayed no remarkable changes during the year. The subjects with pigeon breeder's disease had a more active immune responsiveness to avian contact, and the association of the highest levels with periods of maximal contact with antigen may have an important bearing on the dynamic nature of this condition.

The density dependence of maximum flow in ten atopic asthmatics was assessed by response to breathing a helium-oxygen mixture. They were then subjected to bronchial challenge by Dermatophagoides pteronyssinus and density dependence re-assessed during early and late bronchial reactions. There was considerable individual variation in the density dependence before challenge and in the change in density dependence during induced bronchospasm. However, for any given individual the results were similar during early and late reactions. This suggests that the major site of airflow obstruction may vary from one asthmatic to another but that when antigen challenge is followed by a dual early and late reaction the site of obstruction is similar at each stage.

A double-blind cross-over study lasting 16 weeks was conducted to establish if a twice daily regimen of beclomethasone dipropionate (BDP) was as effective in controlling asthma as a four times daily regimen. The patient's need for inhaled steroids (100 mcg BDP qds) was confirmed prior to entering the study by deterioration of peak expiratory flow rates and/or increased bronchodilator usage during a single-blind placebo period of 6 weeks. Thirty six asthmatics were eligible to enter the study and completed both treatment periods. Daily record cards of symptom scores, four times daily peak expiratory flow rate measurements and inhaled bronchodilator usage were recorded throughout the study. There was no significant difference between the mean PEFR measurements taken four times each day and the variability in PEFR, between the two treatment groups. Symptom scores for cough, wheeze, breathlessness and overall disability also showed no significant difference. Symptomatic inhaler usage for the two groups was similar. Lung function measurements of FEV1, FVC and VC were almost identical; FEV1 being 2.1 l on twice daily regimen and 2.2 l on four times daily regimen. A slight variation was observed in PEFR taken at the end of each treatment period at the clinic visits, being 361 l/min on twice daily and 380 l/min on four times daily drug dosage. In stable asthmatics, the control of asthma measured both symptomatically and by daily lung function was independent of dosing schedule, but twice daily treatment may well lead to better compliance.

There was a reduced prevalence of symptoms of Extrinsic Allergic Alveolitis (EAA) among the cigarette smokers in a survey of 102 volunteer pigeon breeders. These smokers had a significantly lower antibody response against the inhaled antigens associated with the disease; only one of twenty-three smokers (4.3%), but thirty-nine of sixty-five non-smokers (55.4%) had elevated serum IgG antibody levels, despite similar degrees of avian exposure in each group. The appearance of antibody in six of fourteen ex-smokers (42.9%) suggested that the apparent inhibitory effect of smoking on the antibody response was reversible. The smoking group had lower total serum IgG and IgA, higher serum IgD, and their total IgM and IgE levels were similar to the nonsmokers.

Thirty extrinsic asthmatics were challenged by inhalation with Dermatophagoides pteronyssinus extract. In twenty-four an immediate reaction was observed and in sixteen this was followed by a late reaction. Those with late reactions tended to have more severe asthma but did not report greater sensitivity to housedust mite. The occurrence of a late reaction was not related to the degree of airways obstruction before challenge or to the intensity of the immediate reaction. Patients in whom the early reaction was induced by a low dose of inhaled antigen were those most likely to develop a late response. Results of histamine challenge testing suggested that this greater sensitivity of the airway might in part be due to greater non-specific bronchial reactivity.

Pigeon bloom, a waxy powder which coats the feathers of racing pigeons, has been investigated as a potential antigen in pigeon fanciers' lung. Precipitins to a soluble bloom-extract were demonstrated in fifty-nine of ninety-seven people studied at two Scottish-pigeon shows, whilst precipitins to pigeon serum were found in thirty-seven. A radioimmunoassay was developed to allow an estimation of the intensity of antibody response to this antigen in nineteen pigeon fanciers being investigated for pigeon fanciers' lung. The mean antibody level to bloom extract was significantly higher (P less than 0.05) in those with acute symptoms compared to those with less severe symptoms. Pigeon bloom is a highly antigenic material and provides an alternative to pigeon droppings as a source for the inhalant antigens regularly encountered by those keeping pigeons.

The incidence and characteristics of P1-antibodies in Scottish pigeon fanciers has been assessed. Of 223 individuals participating in the study, 23.3% were P1-negative and of these, 53.9% had detectable P1-antibodies. These antibodies were shown to belong to the IgM class and the highest serum levels were found in those pigeon fanciers with symptoms of respiratory disease who were sensitized to pigeon antigens. Of pigeon fanciers' sera, 10.3% gave false positive reactions for the Hepatitis B surface antigen in a reversed passive haemagglutination test. The reactions were most prevalent in sensitized fanciers and were shown to be directed not against the absorbed HBsAg antibody, but against the turkey red cells used as carriers in the test. No relationship was observed between the existence of P1-antibodies and false-positive hepatitis reactions. It was concluded that the inhalation of avian antigens by pigeon fanciers can induce the production of at least three distinct populations of antibodies. No evidence was obtained to imply any special role for P1-antibodies in the aetiology of pigeon fanciers' disease.

A group of nineteen normally healthy subjects in a microprocessor factory reported various degrees of work-related respiratory and systemic symptoms that in some were suggestive of humidifier fever (HF). They all had normal serology against a variety of infectious agents, but serum-precipitating antibody against antigens in the factory humidifier water was present in twelve subjects, primarily those with symptoms most in keeping with HF. There was extensive serological identity between the antigens from this and other confirmed sources of HF. The antibody-positive subjects were all non-smokers and had significantly raised serum IgG. Nine months later, following modification of the humidifier system, the symptoms had resolved in fourteen of the nineteen subjects, the precipitins were reduced in seven but persisted in five subjects, and the total IgG levels were significantly reduced in all subjects. The measurement of total, as well as specific, IgG may be of value in assessing this disease.