Endotoxin, histamine-sensitizing factor and lymphocytosis-promoting factor contents of pertussis vaccines produced in Japan.

The amounts of endotoxin, histamine-sensitizing factor and lymphocytosis-promoting factor contained in combined diphtheria-pertussis-tetanus and combined diphteria-pertussis vaccines recently produced in Japan were determined and the relationships among them were statistically analyzed. The estimated values in histamine-sensitizing units (HSU) and lymphocytosispromoting units (LPU) per human dose ranged from 0.3 to 6 and from 0.4 to 5, respectively. A fairly wide range of endotoxin contents, which were expressed in body weight-decreasing units (BWDU), was also demonstrated. All the ranges were larger than those expected from experimental error. There was a positive correlation between the HSU and LPU values although the individual HSU-LPU ratios ranged from 0.3 to 3, but the range was markedly larger than the width of the 95% confidence interval of the mean ratio. Negative correlation between BWDU and LPU was also significant, probably because of the relatively large number degrees of freedom, though the coefficient was fairly small; while that between BWDU and HSU was not significant. The frequency distribution of individual values of HSU was divided into two lognormal distributions. With one of the two groups obtained by this subdivision, a distinct positive correlation bewteen HSU and LPU was demonstrated, but with the other group there was little correlation. Some differences between the two groups were also found in the correlations between BWDU and the other two variates. No factors responsible for the separation of the groups have yet been found.