Bacteriological studies: 1. The influence of immune serum on the biological properties of pneumococci.

  • Great Britain. Ministry of Health
Date:
1923
Catalogue details

Licence: Public Domain Mark

Credit: Bacteriological studies: 1. The influence of immune serum on the biological properties of pneumococci. Source: Wellcome Collection.

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    longer when inoculated into the subcutaneous tissues, where they give rise to a localised abscess. The following is the record of an bineWeGandfiil attempt to demonstrate the production of rough forms of pneumococci in an immunised mouse. A virulent Type I. culture in broth was mixed with an equal quantity of a Type I. serum and incubated for half an hour, after which the mixture was inoculated intra- peritoneally into two mice. A small amount of peritoneal fluid was withdrawn from each mouse one and two hours later, part of which was sown on plates. Only smooth colonies of virulent type grew, but mice inoculated with the rest of the fluids remained well. The two original mice were killed 20 hours after inoculation and the peritoneal cavities were washed out with salt solution. The centrifuged deposits from the washings were sown on blood agar plates; no growth of pneumococci was obtained. If there is an intermediate stage in the mechanism of protec- tion during which rough attenuated pneumococci, that is, cocci which have not developed the part of their external structure associated with the secretion of soluble substance, are produced in a passively immune mouse, it is clear that they would readily be destroyed, since even large doses of these R cocci inoculated into an unprotected mouse quickly disappear. On the other hand, it may not be necessary to postulate such an intermediate stage. The immune serum may protect the mouse by depriving the pneumococcus of its virulent potentialities, possibly by precipitating the external covering associated with capsule formation and the secretion of soluble substances. The pneumococci so affected would become the prey of the phagocytes. They would, if removed from the animal before destruction, be capable of multiplying, and as the exposure to the immune serum had been brief, they would produce normal virulent descendants. But if within the animal body some sensitised pneumococci escaped the attacks of the leucocytes and divided, the descendants would remain under the influence of the serum, in which case the property of the serum to produce progressive attenuation might be brought into action. DISCUSSION OF RESULTS. 1. The first point of interest which emerges from this study of S and R forms of pneumococci is the fact that a definite morphological criterion has been found to distinguish between virulent and attenuated strains. Further evidence of attenuation is furnished by serological reactions, in particular by the loose character of the clumps in the agglutination test, and by the absence of specific soluble precipitable substance. Given these data. it will be possible to decide whether a culture is in the condition suitable for the production of disease. 2. An important practical corollary will be that, for the production of good immune sera, strains should be used which consist entirely of S forms. Immunisation of rabbits with the cS)
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