OPSONINS 189 



clement unites firmly with the object which is to l)o opsonized, while the thermo- 

 labile clement seems to remain free in the fluid (ITektocn).^' 



It would seem that opsonization and phagocytosis constitute but one of a series 

 of similar processes by which foroif:;n proteins are removed from the blood and tis- 

 sues; i. e., by lysis by extracellular enzymes when this is possible, as it is with 

 simple protein aggregates (albuminolysis )and with some of the more labile cells 

 Oiemolj'sis, bacteriolysis); but in the case of more resistant structures, notably 

 Gram-positive cocci and acid-fast bacilli, extracelhilar lysis being unsuccessful, 

 these protein structures are taken within the cells where a greater concentration of 

 enzymes may destroj"- them. Fundinncntnlly serum hndcriolysis and phagocytosis 

 seem to he the same — in each case specific antibody sensitization prepares the bacterium 

 for lysis by enzymes,' either inside or outside the cells that furnish the lytic enzyme. 



As yet nothing is known concerning the change brought about in the bacteria 

 by the opsonin, although it has been established that it is the bacteria that are 

 modified and not the leucocytes. The chemical nature of the opsonins is likewise 

 unknown, except that they may combine with certain inorganic ions and are then 

 inert (Hektoen and Ruediger),''' since addition of CaCU, BaClj, SrCl2, MgCU, 

 KoSO^, NallCOs, sodium oxalate and potassium ferrocyanide, inhibit the opsonic 

 efTect of serum. On the contrary, calcium salts stimidatc the phagocytic effect of 

 leucocytes, salts of barium and strontium being inactive."* In common with other 

 immune bodies, opsonins are thrown down in the soluble serum globulins.'^ 

 They are very sensitive to acids and alkalies, being destroyed by a concentration 

 of n/i and their maximum effect is at the neutral point." However, treatment of 

 either the bacteria or the leucocytes with very weak acids or alkalies, increases 

 the rate and amount of phagocytosis (Oker-Blum)."' Opsonins may be developed 

 by immunizing against substances practically tree from protein, c. g., melanin 

 granules."^ Injection of nu 'lein preparations may in<'rease the amount of opsonin 

 present in the blood. ^° Cholesterol in excess dimini.shes phagocytosis, but appar- 

 ently through its action on the leucocytes.*' Both the sensitization of bacteria 

 and their ingestion by leuco-^j^tes, either with or without sensitization, tajj^e place 

 in accordance with the laws regulating an adsorption process (LediilEham,*^ 

 S^-hutze'8). ^. 



THE MEIOSTAGMIN REACTION 



Reav'tion of antigens with their specific antibodies results in lowering the sur- 

 face tension of the solution in which the reaction occurs, which may be demonstra- 

 ted by counting the number of drops of the fluid per minute, under constant 

 conditions. Ascoli and Izar*' worked out methods for practical application of this 

 phenomenon, gi\ang it the name of "meiostagmin reaction," from the Greek, 

 meaning "small drop." The number of drops from a stalagmometer is counted, 

 and an increase of two or more per minute is considered a positive reaction, after 

 two hours' incubation of the reacting mixture; the in.'rease is seldom above eight 

 drops. This reaction is said to be sharply specific and extremely delicate, detect- 

 ing antigens diluted up to 1 in 100,000,000 or more. The antigens used are soluble 



"Sawtchenko (Arch. Sci. Biol., 1910 (15), 145; 1911 (16), 161) holds that 

 there are two steps in phagocytosis: (1) Fixation of the bacteria to the leuco- 

 CA'te because of modification of surface tension by the fixative substance (opsonin 

 or amboceptor-complement complex); (2) Ameboid motion of the phagocyte; 

 an entireh^ independent phenomenon. Neither phase of phagoc3'tosis can occur 

 in the absence of electrolytes. 



^* Jour. Infect. Dis., 1905 v2), 129. 



l^ Hamburger, Biochem. Zeit., 1910 (24), 470; 1910 (26), 66. 



"^ See Simon et al., Jour. Exp. Med., 1906 (8), 651; Heinemann and Gatewood, 

 Jour. Infec. Dis., 1912 (10), 416. 



"" Xoguchi, Jour. Exp. Med., 1907 (9), 454. 



^8 Zeit. Immunitat., 1912 (14), 485; Schutze, Jour. Hvg., 1914 (14), 201. 



'^Ledingham, Zeit. Immunitat., 1909 (3). 119. 



80 Bedson, Jour. Path, and Bact., 1914 (19), 19.. 



81 Dewev andNuzum, Jour. Infect. Dis., 1914 (15), 472. 



82 Jour. Hvg., 1912 (12), 320. 



83Munch. med.Woch., 1910 (57), 62, 182 and 403. 



