416 



On the Factois Concerned in Agglutination. 

 By H. E. Dean, M.A., M.B., Ch.B., M.R.C.P., Assistant Bacteriologist, 

 Lister Institute, London. 



(Communicated by Dr. C. J. Martin, F.R.S. Received October 13, — Read 

 December 7, 1911.) 



Of the various reactions which can be observed to take place between 

 antigen and antibody, agglutination has usually been looked upon as 

 relatively simple. It has been assumed that the clumping of bacteria or 

 red cells is produced by the action of substances known as agglutinins. 

 According to the well-known views of Ehrlich, an agglutinin is possessed 

 of two groups, a cytophile or haptophore group which fixes on to the cell, 

 and a group which has the property of producing agglutination. According 

 to another view the cell or bacterium combines with its specific antibody, 

 and the combination of cell and antibody is then clumped by the action of 

 electrolytes. A broad distinction has, however, always been drawn between 

 such phenomena as precipitation and agglutination, which appear to 

 represent a comparatively simple reaction between antigen and antibody, 

 and those more complex effects such as haemolysis and bacteriolysis in which 

 another constituent of serum, the alexine or complement, is necessary to 

 complete the specific action of the antibody. 



Observations published by Muir and Browning (1906) suggested, how- 

 ever, that in some instances, at any rate, the mechanism of agglutination 

 may be more complex. 



It was found that fresh ox serum powerfully agglutinated a suspension of 

 ox corpuscles in the presence of antiserum obtained from a rabbit which 

 had been injected with ox corpuscles. The fresh serum could augment to a 

 very marked degree the agglutinative properties of the homologous anti- 

 serum. This agglutination of red cells by immune body and complement 

 took place rapidly at 37° C, and somewhat more slowly at room temperature ; 

 at 0° C. the agglutination was imperfect. In another experiment, however, 

 complete agglutination was obtained at 0° C. by mixing the red corpuscles 

 of a guinea-pig, the homologous antiserum derived from a rabbit, and fresh 

 ox serum. The property possessed by ox serum of furthering agglutination 

 was destroyed by heating the serum for an hour at 55° C. 



In the same year Bordet and Gay (1906) gave an account of a series of 

 very similar experiments. Bordet and Gay independently discovered the 

 agglutinative property of ox serum for sensitised red cells. They found, 



