A new biological assay method for histamine-sensitizing factor using survival time as a response

Interaction of Haemophilus influenzae type b conjugate vaccines with diphtheria-tetanus-pertussis vaccine in control tests

The effects of combining three Haemophilus influenzae type b (Hib) capsular polysaccharide vaccines, conjugated to different proteins, with DTP vaccine on the subsequent control testing were examined. The addition of the Hib vaccines had little effect on the reactogenicity or the potency of the whole-cell pertussis component. The potency of, and antibody responses to, the diphtheria component were also unaffected in all three combinations. However, combination with the Hib vaccine comprising polysaccharide conjugated to tetanus toxoid resulted in a fivefold potentiation of the tetanus potency and large increases in the antibody responses to tetanus toxin and toxoid and Hib polysaccharide. These results have implications for the control testing of combined vaccines containing a whole-cell pertussis component and Hib polysaccharide-tetanus protein conjugate vaccine.

Multicorrelation analyses of toxic and antigenic components of DPT and DP vaccines produced in Japan

The combined diphtheria-pertussis-tetanus and combined diphtheria-pertussis vaccines, of which the contents of endotoxin, LPF and HSF were reported in the previous paper, have been tested for the respective potencies of pertussis, diphtheria and tetanus components. In order to obtain some information concerning possible adjuvanticities of the toxic components of pertussis cells, relationship between respective toxic activities and the potencies of the respective antigenic components were tested by applying the multiple regression analyses. The results showed that the effects of the toxic components were fairly complicated. Within the ranges of contents of the respective toxic components of the vaccines used in the present experiment, LPF appeared to enhance all the three potencies as the content increased, while the effects of endotoxin and HSF were either enhancing or suppressive depending on the antigenic components.

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.

Attempts at analysis of toxicity of pertussis vaccine. III. Effects of endotoxin on leukocytosis in mice due to lymphocytosis-promoting factor and reference preparations for determination of lymphocytosis-promoting factor

The effect of bacterial endotoxin on the change in peripheral leukocyte population in mice due to the lymphocytosis-promoting factor (LPF) was investigated. Endotoxin affected not only the total leukocyte count but also the leukocyte proportions at any observation time. Both the coefficient and the intercept of regression of the leukocytic response on dose of LPF were modified by endotoxin. Therefore, in a valid biological assay for LPF using the peripheral leukocyte count as a response, a common reference preparation available for any test materials, irrespective of presence or absence of endotoxin, will be impracticable. Two reference preparations were tentatively established, one being a vaccine and the other an LPF preparation containing little endotoxin. A unitage of LP activity was assigned to each reference preparation. The results also showed that an LPF material to be tested for its possible effects on the lymphatic tissues or the reticuloendothelial system should be free from endotoxin.