8o8 THE FUNCTIONAL ROLE OF AGGLUTININS 



Govaerts' and Le Fevre de Arric^ have shown that bacteria flocculate more readily in 

 unheated plasma than in unheated serum, and more rapidly when platelets are pres- 

 ent. These observations suggest the possibility of a greater activity of antibodies, 

 especially agglutinins, in vivo than in vitro, as suggested by Bull. It would appear also 

 that the platelets, although not an essential element in the removal of bacteria, yet 

 may assist the agglutinins in the formation of clumps. 



FACTORS RELATED TO infra vitam AGGLUTINATION 



The importance of the fixed-tissue cells in relation to agglutination and other 

 factors in the ultimate disposal of invading bacteria has become evident from a num- 

 ber of investigations. As already pointed out, Bull's observations on the intravascular 

 agglutination of various bacteria which are phagocyted by the cells in the lungs, liver, 

 and spleen has thrown light on the mechanism of immunity to many infections and 

 further emphasizes the relationships which must frequently exist between antibodies 

 in the blood stream, notably the agglutinins and opsonins, on the one hand, and the 

 cellular elements, on the other. However, in certain cases it would appear that the 

 latter may be the predominating or only factor in the immunity process. Kyes^ has 

 shown that in the pigeon, a species insusceptible to the pneumococcus, the infecting 

 organisms are rapidly withdrawn from the general blood stream and localized in the 

 liver, and especially in the spleen. In these organs the ultimate localization of the 

 pneumococci is within a type of fixed phagocyte — the hemophage — common to both. 

 This phagocytic destruction of the micro-organisms was found to be so extensive and 

 so rapid that it appeared to be the most important if not indeed the determining 

 factor in the establishment of this instance of natural immunity. It did not appear 

 that agglutination played an important role. Instead of a clumping of the bacteria 

 there occurred a filtration by the peculiar structural arrangement of the capillaries of 

 the spleen. 



Recently Hopkins and Parker^ have also shown the great importance of the fixed- 

 tissue cells. These investigators injected streptococci into rabbits and cats and found 

 that the organisms were rapidly removed from the circulation, the removal being 

 largely due to phagocytosis carried on by the endothelial cells in the lungs and by sim- 

 ilar cells in the liver and spleen. These investigators were unable, however, to apply 

 Bull's results to the removal of streptococci from the circulation on the basis of ag- 

 glutination. Other workers have also failed to find evidence of the dominating in- 

 fluence of agglutinins in certain infections. TenBroeck^ points out that these anti- 

 bodies are of little importance in infections with the hog-cholera bacillus. 



Some interesting observations bearing directly on the factors concerned in the 

 rapid and complete disappearance of injected pneumococci from the blood of immun- 

 ized rabbits were made by Manwaring and Coe.'' It was shown that, besides the proc- 

 ess of agglutination emphasized by Bull, another factor is also operative in the re- 



' Govaerts, P.: CompL rend. Soc. de biol., 83, 196. 1920. 



^ Le Fevre de Arric, M.: ibid., p. loii. 1920. 3 Kyes, P.: /. Infect. Dis., 18, 277. 1916. 



" Hopkins, J. G., and Parker, J. T.: /. Exper. Med., 27, 1. 1918. 



sTenBroeck, C: ibid., 26, 441. 1917. 



'Manwaring, W. H., and Coe, H. C.: /. ImDiiinol., i, 401. 1916. 



