Extraction of a monospecific Coombs-reagent from chicken eggs

During the last ten years the extraction of specific antibodies (ab) from the yolk of eggs of immunised chickens is more and more accepted as an useful alternative to the immunisation of mammals. The subject of this work is the immunisation of chickens with human IgG and the extraction of specific anti human IgG ab from egg yolk in order to obtain monospecific Coombs reagent. 12 Leghorn hens (25 weeks old) were immunised with intact human IgG (INTACGLOBIN). The chickens were immunised with 100 microg IgG/animal once per week for a period of seven weeks. The highest titre was observed after the 5th immunisation, the following immunisations achieved no further titre increase. The IgY purification was performed according to the method of Akita and Nakai (1993). The resulting IgY preparation was tested for the presence of hetero-agglutinine by means of direct agglutination using human erythrocytes of all blood groups. Thereafter 58 blood donors were tested by means of direct or indirect Coombs-test using a reference reagent (DAKO) and a Coombs reagent isolated from chicken eggs (IgY antibodies). No differences have been found between the results obtained using both Coombs reagents. Presented results show that there is a possibility to produce Coombs-reagent in chickens. Advantages of this method are: 1) non invasive antibody sampling by egg collection instead of bleeding the animal (refinement of antibody production); 2) decreasing amount of animals necessary to produce high amounts of reagent; 3) IgY-preparation contains no hetero-agglutinine in contrast to serum ab from mammals, therefore additional step in reagent production e.g. the absorption of hetero-agglutinins is not necessary.