Studies with sputum: II. Antigenicity of asthmatic sputum: Hemagglutinating and precipitating activity of rabbit antisputum sera

Abstract

1. 1. Sterile suspensions of sputum derived from an asthmatic subject of Type A proved antigenic when injected into rabbits by the intravenous route. Immunologic responsiveness of the rabbits consisted of anaphylactic reactions and the production of high titers of hemagglutinins for erythrocytes of the same blood group as the patient, with some cross reaction for blood groups of the heterologous type. An anamnestic reaction did not occur when a booster injection was given to such immunized rabbits after a rest period. 2. 2. The rabbit antisputum serum so obtained yielded multiple precipitate bands in gel diffusion against homologous and heterologous sputa. Distinct bands of precipitate were also obtained when the serum was diffused against lysates of human erythrocytes of type A, B, or O. The bands of precipitate with the lysates yielded reactions of identity with one of the multiple bands against sputum. 3. 3. Absorption of rabbit antihuman sputum removed the hemagglutinins for the absorbing cell type. This did not, however, appear to remove the precipitin for the lysate. Although some of the precipitate bands with sputum were eliminated from the absorbed serum, there were still several precipitate bands remaining. 4. 4. Controlled studies with soluble bacterial extracts of the usual flora of the respiratory tract yielded no precipitate bands when diffused against rabbit antisputum serum. Conversely, a precipitin to a bacterial extract failed to yield bands when sputum was diffused against it. 5. 5. All of eight preparations of sputa which were tested against a strong rabbit antihuman serum albumin yielded positive precipitin bands which indicated the presence of an albumin in all of the sputa derived from persons suffering from inflammatory discase of the respiratory tract. The limiting value of the detection with the sera studied was of the order of 5 gamma per 0.2 ml. and it was estimated that the sputum preparations contained between 5 gamma and 50 gamma per 0.2 ml. At least one of the multiple precipitin bands between sputum and rabbit antisputum serum was probably the albumin-anti-albumin system. 6. 6. Rabbits immunized with purified blood group substance derived by phenol extraction after pepsin digestion of human sputum developed no anti-body, which is consistent with previously recorded findings with purified blood group substance of other animal origin. Since the whole sputum is very antigenic with respect to production of anti-blood group antibodies (in agreement with Baer's observations with ovarian cyst fluid) it would appear that the blood group substance in human sputum is in a conjugated and antigenic form. 7. 7. The significance of these observations in relation to future investigations is briefly discussed.