The observation that ABO agglutinins are present in a wide variety of pollens (Denborough, 1964) and so must commonly be inhaled, and the knowledge that plant agglutinins are antigenic (Mikela, 1957) , prompted us to study secretor status in allergic disease of the respiratory tract, namely in asthma and hay fever. The opportunity has been taken to measure the amount of isoagglutinins present in the serum and saliva of these subjects at the same time. Materials and Methods Tests were carried

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... on 435 subjects with asthma and hay fever and 411 healthy control subjects. Some of the subjects with asthma and hay fever were attending Allergy Clinics in Melbourne or the Asthma Foundation of Victoria, some were volunteers from the University of Melbourne, and some were blood donors. Of the 435 patients, 182 had asthma alone, 140 had asthma and hay fever, and 113 had hay fever alone. All the subjects with asthma had unequivocal histories of recurrent airway obstruction without chronic respiratory infection, and those with hay fever gave a history of typical recurrent attacks. Both seasonal and perennial varieties were included. The complaints were seasonal in 53 (29%) of the subjects with asthma alone, in 80 (57%) of those with asthma and hay fever, and in 100 (88 5%) of the subjects with hay fever alone. The 411 controls were all healthy blood donors without a history of asthma or hay fever. The mean age in the group with asthma and hay fever was 41X1 + 16-0 years and in the controls it was 36-3 + 12-1 years. Samples of blood were obtained from all subjects and samples of saliva were collected from 404 of those with asthma and hay fever and from 353 controls. Because there is a seasonal variation in the titre of serum isoagglutinins (Shaw and Stone, 1957), the samples were collected from the subjects with asthma and hay fever and from the controls sequentially. The sample of saliva was collected without artificial stimulation. Half ofthe sample of saliva was stored immediately at -150 C. until tested for the presence of agglutinins. The other half, for the test of secretor status, was placed in a boiling water bath for 10 minutes before storage at -150 C. ABO Blood Group. The ABO blood group was assessed by the use of the standard tube method. Secretor Status. The secretion of ABH antigens in the saliva samples was measured by doubling-dilution agglutination inhibition tests. Samples from a known secretor and non-secretor were tested at the same time. A saline extract of the seed of Ulex europaeus was used as a source of anti-H. Each inhibition titration was given a score; complete inhibition counted as 10, ± as 8, + as 6, ++ as4, +++ as2,and ++++ asO. Asubject was regarded as being a non-secretor if his total salivary score was less than 20. Agglutinins. The amount of isoagglutinins present in serum and saliva was determined using a standard 12tube doubling-dilution titration. Control samples containing known amounts of isoagglutinins were tested at the same time. The results were read macroscopically and the amount of agglutination present was recorded as + + + +, + + +, + +,+, or 0. The last tube showing + agglutination was recorded, and each titration was also given a score, each + counting as 1. The tubes for secretor tests and agglutinin titres were read by a single observer. Individual scores were closely reproducible. Results Of the subjects with asthma and hay fever, 196 were men and 239 were women. There were 221 male and 190 female controls. Table I shows that the ABO blood group distribution in the two groups was similar over-all and in both sexes, and differed little from the distribution in a large Australian defence force series (Bryce et al., 1950) . Secretor status was tested in 404 subjects with asthma and hay fever and 353 controls (Table II) . There was no significant difference in the incidence of secretors in either sex between the two groups. Though fewer individuals with asthma and hay fever had isoagglutinins in their saliva than controls, the only statistically significant differences between the groups were in the over-all incidence of anti-A saliva agglutinins in subjects belonging to group 0 (X2 = 6-0 for 1 degree of freedom; p < 0-05), 02