FILTRATION OF IMMUNE SERUMS. 



By E. H. RuEDiGER. 

 [From the Serum Section, Biological Laboratory, Bureau of Science, Manila, P. I.) 



Because of the difficulties encountered in endeavoring to obtain anti- 

 serums for therapeutic purposes free from corpuscles^ precipitates, and 

 bacteria, it was thought advisable to study the effects of filtration through 

 Berkefeld filters on immune serums. Early in the year 1906 attempts 

 to filter anticattle plague serum had been made in this laboratory, but were 

 soon abandoned because the filters invariably became clogged. 



More recently filtration of serum was again attempted and it was 

 found that the serum readily passes through the filter, provided that it is 

 free from blood corpuscles, precipitates and other extraneous matter. 

 These substances as a rule are removed easily from the serum by 

 centrifugating for thirty minutes at a speed of 3,000 revolutions per 

 minute, and at the present time all serums prepared by this laboratory 

 are passed through a germ-proof filter prior to bottling. The serum 

 thus obtained is perfectly clear and is free from bacteria which may have 

 entered accidently during the process of handling. 



TECHNIQUE. 



The serum, having been collected, is centrifugated at a speed of 3,000 

 revolutions per minute for thirty minutes, which process usually renders 

 it fairly clear. It is now passed through a clean, sterile Berkefeld filter 

 marked N or W. If, after centrifugating, the serum is not clear, it is 

 advisable to first pass it through a Berkefeld V filter to remove most of 

 the extraneous matter which might lead to rapid clogging of the finer 

 grained filter marked N or W. Using an apparatus of one liter capacity, 

 one liter of sei-um under two atmospheres pressure should pass through 

 the Berkefeld filter Y in three minutes or even in less time, while with 

 the N filter not more than five minutes should be required. A ten-liter 

 filtering apparatus should deliver a liter of serum through Berkefeld V 

 filter in one minute, and not more than three minutes per liter should 

 be required when an N filter is used. 



Care must be taken to cleanse the filter after it has been used. Any 

 serum left in the pores of the filter will be coagulated by autoclaving and 



