In the foregoing paper (1) it has been shown that while strains of Pneumococcus Type III incapable of multiplication at 41°C. are avirulent for the rabbit, not all strains able to persist and to grow at this temperature are equally lethal for that animal. Two smooth strains of the latter group exhibiting a striking disparity in their rabbit virulence have been studied more closely, and evidence obtained which indicates that the variation in virulence among such strains may depend at least partly on differences in size of the capsule and the rate at which this structure is lost.The findings suggested an inquiry as to whether the capsular characteristics depend on factors which can be varied in the manner in which it has been demonstrated by Grittith (2), Dawson (3) and others that type specificity can be altered, or whether they might be the result of more stable physiological processes, which, although temporarily inapparent during existence in the R phase would again reappear unchanged on the resumption of the S form, regardless of whether the
In an accompanying paper it has been shown that two strains of Pneumococcus T y p e I I I differing in rabbit virulence could be dis-. tinguished in respect to the rate at which the capsule diminished during cultivation in various media. Concomitantly with the progressive loss of capsular substance, changes in the surface properties of the organisms were demonstrated which ultimately, but after different periods, reduced each strain to a state in m a n y respects resembling that of the R form. The principal objective of the experiments to be presented here was to reveal a relationship between these facts and the events which ensue when the organisms are introduced into the animal body. Materials and TechniqueStrains of Pneumococci.--The two strains of Pneumococcus Type III designated SV and CH, and the R variant derived from each as described in Paper II were used throughout these experiments, as well as a stock R derivative from Pneumococcus Type I.Animals.--In all cases, unless specific descriptions are given in the text, albino rabbits ranging in weight from 1600 to 2000 gin. and white mice of 15 to 20 gin. weight were used.
Experimental evidence presented in Paper III* indicates that removal and destruction of both rabbit virulent and avirulent strains of Pneumococcus Type III in the normal animal are brought about by the same means, namely, the phagocytic cells of the body, provided the integrity of the capsule becomes impaired. It leaves unanswered, however, the interesting q~aestion as to whether this phagocytosis is "spontaneous," that is, taking place without the intervention o£ a serum component, or whether the adjuvant action of an antibody is essential to the process. The following experiments although they fail to give a complete answer do nevertheless reveal the participation of an antibody reacting with the somatic C carbohydrate of Tillett, Goebel and Avery (1) which not only appears to play a r61e in the phagocytosis of normal animals but is probably responsible for bringing about the non-type specific immunity which Tillett (2)obtained in rabbits vaccinated with R pneumococcus or the smooth form of a heterologous type. Methods and Materials
1. The A carbohydrate isolated from Type I pneumococcus by Pappenheimer and Enders, on the basis of elementary analysis, the presence of the acetyl group and its immunological properties, appears to be identical with the acetyl polysaccharide described by Avery and Goebel. 2. The A carbohydrate possesses a greater anti-opsonic action than either the deacetylated substance obtained by boiling in alkali or the soluble specific substance of Type I pneumococcus prepared according to the procedure of Heidelberger, Goebel and Avery. The opsonic titre of normal human serum is practically eliminated upon the addition of the A carbohydrate—an effect not observed with equivalent amounts of either the deacetylated material or the specific soluble substance. In immune serum, the A carbohydrate brings about a quantitatively greater reduction in opsonic activity than its derivatives, but it has not been possible to demonstrate complete inhibition of phagocytic action by the method of absorption of antibody. 3. In a system of normal human serum and leucocytes capable of destroying Type I pneumococcus, the bactericidal effect maybe entirely removed upon the addition of the A carbohydrate. It proved impossible to inactivate the bactericidal action with the deacetylated substance in equivalent proportions. In this system, the A carbohydrate was about 64 times more effective as an antibactericidal agent than the deacetylated compound. Essentially similar results were obtained in a study of the antibactericidal properties of the A carbohydrate and the deacetylated derivative in the presence of anti-Type I pneumococcus rabbit serum added to a mixture of exudative leucocytes and the defibrinated blood of the rabbit. 4. The mouse-protective titre of anti-Type I pneumococcus rabbit serum is lowered to a greater degree after absorption with the A carbohydrate than it is by similar treatment with the deacetylated compound. Absorption with the A carbohydrate does not, however, completely remove the protective antibody. 5. As Avery and Goebel have shown in the case of the acetyl polysaccharide, so the A carbohydrate, when administered in very small quantities, protects mice against an otherwise fatal dose of Type I pneumococcus. Active immunity in mice has been obtained with as little as 0.00005 mg. of the A carbohydrate administered in a single dose. Doses larger than 0.005 mg. confer no protection on these animals. Deacetylization of the A carbohydrate after boiling in N/10 sodium hydroxide destroys its protective capacity while similar treatment in N/50 alkali does not completely remove its immunizing property. Active immunity may arise within 3 days following a single injection of the A substance. It appears to be at its height from 6 to 25 days thereafter, and is retrogressive by the 49th day following vaccination. Injection of the A carbohydrate into immunized mice immediately before infection deletes the state of resistance. 6. The immunity actively induced as a result of injection of the A carbohydrate may be passively transferred to normal mice with the serum of vaccinated animals. 7. Since the evidence obtained in the course of this study indicates that the A carbohydrate of Type I pneumococcus and the acetyl polysaccharide of Avery and Goebel represent the same chemical substance, it is suggested that the designation "A carbohydrate" or "A substance" be relinquished in favor of the more exactly descriptive term "acetyl polysaccharide."
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.