482 



The Inhibitory Action upon Subsequent Phagocytosis, exerted on 

 Active Normal Serum by Inactive Normal Serum through 

 which Bacilli have been passed. 



By J. C. G. Ledingham, M.A., M.B. (Aberdeen), Assistant Bacteriologist, Lister 



Institute. 



(Communicated by Dr. C. J. Martin, F.R.S. Eeceived April 30, — Read 



June 13, 1907.) 



Considerable difference of opinion still prevails regarding the nature of the 

 opsonic substances present in normal serum. Wright, Bulloch and Atkin, etc., 

 uphold the view that the opsonin of normal serum is a simple thermolabile 

 body. Muir, on the other hand, regards the opsonin as a body which behaves 

 like complement, while Dean holds that it is essentially thermostable and in 

 all probability co-operates in its action with a thermolabile complement. The 

 demonstration of anti-bodies by complement-deviation experiments (Bordet, 

 Gengou, Pfeiffer and Friedberger, etc.) has recently proved fruitful in 

 •connection with the bacteriolysins, haemolysins, precipitins of immune sera, 

 and the following experiments were designed to test whether, by a similar 

 method applied to phagocytosis, the presence in normal serum of opsonic 

 amboceptors could be demonstrated : — 



Experiment I. 



Normal human serum was heated for 30 mins. at 60° C. (denoted " A "). A very thick 

 emulsion of tubercle bacilli in 1 : 1000 salt solution was added in equal volumes to " A " 

 and kept in contact therewith for 1 hr. 30 mins. at 37° C. The mixture was then centri- 

 fugalised (7000 revolutions per minute) for 1 hr., and the supernatant fluid pipetted off 

 (denoted "B"). 



Equal volumes of " B " and fresh normal human serum were now mixed and kept in 

 contact at 37° C. for 1 hr. (final fluid denoted " T "). 



The steps employed in the preparation of the control fluid were essentially similar to 

 the above. Thus, heated normal serum was added in equal volume to salt solution 

 (instead of to tubercle emulsion) and the mixture kept in contact for 1 hr. 30 mins. at 

 37° C. Equal volumes of this mixture and fresh normal serum were now taken, and 

 retained in contact for 1 hr. at 37° (control fluid so obtained denoted " C "). 



The opsonic contents of " T" and " C" were now compared in the usual way, fresh 

 tubercle and staphylococcal emulsions being employ ed. The result was as follows : — 



Bacilli per leucocyte. 



Test fluid " T " + leucocytes + B. tuberculosis 0*5 



Control fluid " C " + leucocytes + B. tuberculosis 2*3 



Cocci per leucocyte. 



Test fluid " T " + leucocytes + staphylococci 1*4 



Control fluid " C " + leucocytes + staphylococci 3*57 



