TOXIC SUBSTANCES PRODUCED BY PNEUMOCOCCUS

A STUDY OF THE THERAPEUTIC MECHANISM OF ANTIPNEUMOCOCCIC SERUM ON THE EXPERIMENTAL DERMAL PNEUMOCOCCUS INFECTION IN RABBITS : I. THE PRESENCE IN ANTIPNEUMOCOCCIC SERUM OF A NON-ANTIBACTERIAL THERAPEUTIC FACTOR

1. Antipneumococcic serum contains in addition to the antibodies against the various bacterial constituents, a non-antibacterial therapeutic factor. 2. The non-antibacterial factor has been separated from the antibacterial antibodies by absorption with homologous, heat-killed, virulent pneumococci. 3. The non-antibacterial factor is not type-specific; it is probably species-specific; it is not neutralized by concentrated pneumococcus broth culture filtrate. 4. The therapeutic effect of the non-antibacterial factor was demonstrated on the experimental, dermal pneumococcus infection of rabbits; this effect is demonstrable when it is administered per seor in conjunction with a certain subeffective dose of serum. 5. Evidence is presented for the assumption that the ultimate outcome of pneumococcus infection depends to a considerable extent upon this non-antibacterial factor.

STUDIES ON THE OXIDATION AND REDUCTION OF IMMUNOLOGICAL SUBSTANCES : VIII. THE ANTIGENIC PROPERTIES OF HEMOLYTICALLY ACTIVE AND HEMOLYTICALLY INACTIVE MODIFICATIONS OF PNEUMOCOCCUS HEMOTOXIN

The following modifications of the antigen (pneumococcus hemotoxin) were studied: (1) the hemolytically active (reduced) substance; (2) the hemolytically inactive, reversible oxidation product; (3) the inactive irreversible products formed by treatment With high concentrations of H₂O₂; (4) the inactive products formed by heat. The antibody-invoking property of the reversibly oxidized form seemed to be identical with that of the original, hemolytically active or reduced form; neither of the other two hemolytically inactive products invoked antibody production. The same modifications of the antigen which exhibited the antibody-invoking property in vivo possessed the antibody-combining property in vitro; and the modifications which lacked the one property also lacked the other. Evidence is presented that the groups of the hemotoxin molecule in which the true antigenic properties are resident are not necessarily altered by processes which inactivate the groupings responsible for the toxic (hemolytic) action of the original antigen. The lack of antigenic properties on the part of the other two hemolytically inactive modifications is evidence that the treatment employed to alter the toxic property of the molecule must be properly chosen to avoid profound changes which affect the antigenically effective groupings. From an immunological point of view, the reversibility of the antigenically effective oxidation product of pneumococcus hemotoxin is important as an index that the loss of toxicity (hemolysis) was accomplished without a profound change in the molecule. The theoretical significance of the antigenicity of non-toxic modifications of toxic antigens is discussed.

STUDIES ON THE OXIDATION AND REDUCTION OF IMMUNOLOGICAL SUBSTANCES : X. IMMUNOLOGICAL DISTINCTIONS BETWEEN THE HEMOTOXIN AND THE "PROTEIN FRACTION" OF THE PNEUMOCOCCUS CELL

The investigation deals with the immunological differentiation of the hemotoxin and the "protein fraction" of Pneumococcus, and with a like differentiation of the antihemotoxin and the antiprotein precipitins. The distinction is made upon the basis of the following evidence: (1) The antigenic (antibody-invoking and antibody-combining) properties of the hemotoxin were destroyed by heat and oxidation treatments which did not cause the loss of the antigenic effectiveness of the "protein fraction." (2) The removal of the hemotoxin from pneumococcus solutions by combination with erythrocytes caused no loss in the capacity of the solution to invoke the production of antiprotein precipitins nor in its capacity to react with antiprotein immune serum. Titrations of the antihemotoxin content of antipneumococcus horse serum (both diagnostic and therapeutic) indicated that the heating treatment of the immunization material is the most important factor in determining the antihemotoxin content of the immune sera obtained from horses, as well as of that from rabbits. A distinction was also made between the hemotoxin and the toxic substances ("endotoxin") which cause the acute anaphylactoid death of rabbits.

STUDIES ON OXIDATION AND REDUCTION BY PNEUMOCOCCUS : IV. OXIDATION OF HEMOTOXIN IN STERILE EXTRACTS OF PNEUMOCOCCUS

In the present work on oxidation and reduction by sterile extracts of pneumococcus, the preparations employed contain among other constituents, a hemolytic substance the properties of which have been described by Cole (1, 2) in his studies on pneumococcus hemotoxin. Pneumococcus extracts prepared by the methods described are actively hemolytic, 0.005 cc. of extract causing complete lysis of 2.5 cc. of a 1 per cent suspension of red cells from rabbit blood. This hemolytic property of pneumococcus extracts is destroyed by 10 minutes exposure to 55°C. When pneumotoxin-containing extracts are protected from the action of molecular oxygen, their hemolytic activity remains unimpaired for considerable periods of time. In the presence of air, on the other hand, the stability of the hemolytic substance depends upon whether the particular type of extract contains a "complete" or "incomplete" oxidation-reduction system. Sterile broth extracts of unwashed pneumococci are reactive with molecular oxygen, and as a result of this union peroxide is formed whenever these extracts are exposed to air. The hemolytic activity of "complete" extracts of this type is rapidly decreased and finally destroyed in the presence of molecular oxygen. On the other hand, the "incomplete" type of extract prepared by saline extraction of washed pneumococci may be exposed to air with little or no loss of hemolytic power. This "incomplete" washed cell extract, unless reactivated, does not undergo autoxidation in the presence of air; under these circumstances peroxide is not formed and the hemolytic activity of this type of extract is not impaired by exposure to air. The stability of the hemolytic agent in the "incomplete" type of extract is evidence that this substance is itself not reactive with or affected by molecular oxygen, even in the presence of the cell enzymes. The destruction of the same hemolytic substance in extracts capable of undergoing autoxidation may be ascribed to the action of some peroxide formed by the union of molecular oxygen with easily oxidized or autoxidizable substances of the extract. It is now known that a peroxide, having the reactions of hydrogen peroxide, accumulates in sterile pneumococcus extracts during oxidation. It has been shown in the present study that the addition of preformed hydrogen peroxide destroys the hemolytic activity of pneumococcus extracts, although higher concentrations were required than were detected in oxidized extracts themselves. These facts and the known action of superoxides in analogous types of reaction make it seem not unlikely that the active agent in the destruction of pneumotoxin in oxidized cell extracts may be a peroxide; either hydrogen peroxide or some higher organic peroxide formed during autoxidation of the extract.

STUDIES ON OXIDATION AND REDUCTION BY PNEUMOCOCCUS : VI. THE OXIDATION OF ENZYMES IN STERILE EXTRACTS OF PNEUMOCOCCUS

1. Certain enzymes of Pneumococcus are destroyed by oxidizing agents formed when sterile extracts of the cellular substances are exposed to air. The carbohydrate-hydrolyzing enzymes (sucrase, raffinase, inulase, and amylase) are the most easily inactivated under these conditions, although the bacteriolytic enzyme is also reduced in activity. Similar treatment is without effect upon the active concentration of pneumococcus lipase and peptonase. 2. The enzymes which are destroyed during the oxidation of unwashed cell extracts are themselves non-reactive with molecular oxygen. The reactions by which they are destroyed seem to represent oxidations of a type similar to those proposed in previous papers for the oxidation of hemotoxin and of hemoglobin. 3. A study has been made of the relative resistance of different pneumococcus enzymes to heat and to the action of hydrogen peroxide. 4. The various enzymes may be arranged in the same order of relative resistance whether the rating be made from the standpoint of resistance to heat or of resistance to oxidation. Nevertheless, it appears that by a proper regulation of conditions of oxidation, certain labile constituents of a mixture of cellular enzymes may be inactivated with less effect upon the activity of other constituents of the mixture than when inactivation is brought about by heat.

RESULTS OF PROPHYLACTIC INOCULATION AGAINST PNEUMOCOCCUS IN 12,519 MEN

1. From a study of the agglutinins and protective power of the serum of 42 persons vaccinated against the pneumococcus, Types I, II, and III, it is demonstrated that a definite immune response has been secured to Types I and II by the dose of vaccine employed. Little evidence of response to Type III can be demonstrated by these methods, but this is of less significance in that in animals it is relatively difficult to secure antibodies against this strain in the serum, even though a considerable degree of active immunity may have been produced in the vaccinated animal. 2. The degree of response to the vaccination appears to be dependent upon the total dosage of each type of pneumococcus administered. While some response may be elicited by 2½ billion cocci of each type, a much more constant and greater response follows 13 billion. 3. In subcutaneous administration the manner in which the total dosage is divided, whether given in a single large dose, in seven small daily doses, or in three to five moderate doses at 3 to 7 day intervals, seems to have little influence upon the degree of immune response, provided the total dosage is the same. 4. The local and general toxic reaction varies greatly in different individuals. The smaller the individual doses, the fewer are the severe reactions. This makes it desirable to divide the total dosage into as many inoculations as circumstances make practicable. 5. At Camp Upton 12,519 men have been vaccinated against Pneumococcus Types I, II, and III. Three or four doses were given at intervals of 5 to 7 days with a total dosage of 6 to 9 billion of Types I and II and 4½ to 6 billion of Type III. 6. During the 10 weeks that have elapsed since the vaccination, no cases of pneumonia of these three types have occurred among the men who had received two or more injections of vaccine. 7. In a control of approximately 20,000 men there were twenty-six cases of Pneumococcus Types I, II, and III pneumonias during the same period. 8. The incidence of Pneumococcus Type IV pneumonia and streptococcus pneumonia was much less among the vaccinated troops than among the unvaccinated. No explanation has been advanced for this difference. 9. Small sterile infiltrations disappearing spontaneously occasionally follow the injection of large doses of pneumococcus vaccine and appear to be an expression of cutaneous hypersusceptibility. 10. The persons who develop these lesions exhibit local reactions to each dose of vaccine. They also give abnormally marked reactions to intradermal injections of pneumotoxin. They do not, however, exhibit anything notable in the agglutinative or protective powers of their sera after vaccination. Whereas the immune response is characteristically specific for the type of pneumococcus, this reaction is not specific for any type. We have found no evidence that Type III is more prone to elicit these severe local reactions than are Types I and II. 11. Prophylactic vaccination against pneumococcus of Types I, II, and III is practical and apparently gives protection against pneumonia produced by these types. It remains to be determined how long this immunity persists.

THE PRODUCTION OF PURPURA BY DERIVATIVES OF PNEUMOCOCCUS : I. GENERAL CONSIDERATIONS OF THE REACTION

1. Pneumococcus extracts have been shown to be capable of producing hemorrhagic purpura in white mice, rabbits, and guinea pigs. 2. The purpura-producing principle resists heating to 100°C. for 10 minutes; it resists oxidation; it is filter-passing; its activity is destroyed by digestion with trypsin; it is obtained from pneumococcus extracts by full saturation with (NH₄)₂SO₄, after the acetic acid-precipitable substances have been removed from the extracts. 3. The purpura-producing principle is common to all four types of pneumococcus and apparently bears no relation to virulence. 4. The purpura-producing principle is probably a degradation product of pneumococcus. 5. This principle is not associated with the hemotoxin of pneumococcus, since the hemolytic activity of an extract may be destroyed without effect on the ability to cause purpura.

THE PRODUCTION OF SKIN NECROSIS BY CERTAIN AUTOLYSATES OF PNEUMOCOCCUS (TYPES I AND II)

1. Certain pneumococcus autolysates produce necrosis when injected into the skin of guinea pigs. 2. The necrosis-producing principle can be filtered through a Berkefeld N filter, is extremely thermolabile, and is very sensitive to oxidation. 3. The necrotizing poison can be separated from the pneumococcus hemotoxin by adsorption with red cells. This removes the hemotoxin and leaves the necrosis-producing principle unaffected. 4. The necrotizing substances obtained from Pneumococcus Types I and II are neutralized by the antiserum prepared with Pneumococcus I.