Studies on Streptolysin O and Antistreptolysin O I. Spectrophotometric Determination of the Hemolytic Activity of Streptolysin O by the Fifty Per Cent End-Point Titration

Studies on Streptolysin O and Antistreptolysin O Ii. Neutralization Reaction of Streptolysin O by Antistreptolysin O

“…Hence, to economize the material , 1/25 M will be used in the routine ASL titration work (Kusama , 1958 …”

“…In the preceding paper (Kusama et al, 1958) on the spectrophotometric determi MATERIALS AND METHODS 1. SL, rabbit red blood cell (RBC) suspension, buffered saline solution (BS) and neutralized cysteine solution : Cf, preceding paper.…”

“…There are some suggestive evidences that the neutralizing capacity of such sera may be due to the non-specific inhibition of hemolysis rather than due to the specific antibody (Kusama, 1958). Hence, the subsequent experiments aimed to set up a titration procedure which could test the majority of human sera, except these extreme ones, with satisfactory accuracy, STREPTOLYSIN O AND ANTIS TREPTOL YSIN O, II 363 ( Fig.…”

“…3d Tests with 40 and 10 H. U. of the SL : It would be difficult to assess proper ASL titers to human sera, owing to different slopes and combining velocities. To * Calculated in the same way as in the rate of hemolysis (Kusama et al ., 1958 overcome this difficulty, the examinations of reaction curves and combining velocities employing test doses of the SL larger than 10 H.U. were then carried out.…”

“…of the SL, lot 1 or 2 under the standardized conditions, and the routine ASL titration procedure will use the SL dose that would cause 50 hemolysis in the presence of 3.2 units of ASL (Kusama, 1958). Therefore, the amount of the SL (LH50), which would cause 50 % hemolysis mixed with 3.2 units of our standard ASL, was measured for different lots of the SL by examining varying amounts of the SL against a constant dose (3.2 units) of ASL.…”