The purpose ofthis study was

An association between pigeon breeders' disease and serum IgG antibodies to antigens derived from pigeon has been recognised since the first description of this type of hypersensitivity pneumonitis in 1965.'The relationship between exposure, circulating IgG antibody against pigeon protein antigens, and the development of pigeon breeders' disease remains uncertain,2 however, and this is reflected in the results of clinical studies. Patients reported in detail,3 usually with an acute, severe illness, typically have an intense antibody response and are rarely antibody negative4; whereas surveys conducted among the general population of pigeon fanciers regularly identify people who are apparently affected but who lack serum antibodies.5 6 Furthermore, these studies have found an appreciable proportion of healthy fanciers who do have circulating antibody against pigeon proteins, and it has been suggested that the humoral response largely reflects the intensity of exposure. used a radioimmunoassay technique to investigate the humoral antibody response and the factors which influence this and the development of pigeon breeders' disease in a large group of pigeon fanciers. MethodsPigeon fanciers in Central Scotland were approached through meetings organised at their local pigeon racing clubs and any person regularly exposed to pigeons, whether primarily engaged in the hobby or helping a relative with the pigeon husbandry, was asked to complete a questionnaire and provide a 20 ml venous blood sample. The questionnaire was divided into several sections, the questions generally requiring a simple "yes/no" reply. One section related to the circumstances and degree of exposure, another concerned the presence of any immediate or delayed symptoms after contact with the pigeons, and a further section recorded the details of any other illnesses. The completed questionnaires were coded and the data transferred to the disc storage of a PDPI 1/45 computer. Criteria for extrinsic allergic alveolitis were derived from Christensen et al,6 requiring a delayed (6-12 hours after exposure) respiratory symptom, 274 on 9 May 2018 by guest. Protected by copyright.

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 tvi' O 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< 005) 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.

Summary 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.

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-giobulinaemia 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 ofthe highest levels with periods of maximal contact with antigen may have an important bearing on the dynamic nature of this condition.