FURTHER STUDIES ON BACTERIAL HYPERSUSCEPTIBILITY. II

THE CHEMICAL NATURE OF RESIDUE ANTIGEN PREPARED FROM YEAST

Residue antigen recognizable by the precipitin test can be prepared from yeast as from bacteria. The active material appears to be identical with a complex carbohydrate, the "yeast gum" of Salkowski. In the purest form of it obtained small amounts of both nitrogen and phosphorus are still present, either as impurities or as part of the molecule. The yeast gum is not antigenic in the sense of producing antibodies.

SEROLOGICAL REACTIONS IN PNEUMONIA WITH A NON-PROTEIN SOMATIC FRACTION OF PNEUMOCOCCUS

1. Sera from individuals acutely ill with lobar pneumonia possess the capacity to precipitate in high titre a non-protein somatic fraction derived from pneumococci (Fraction C). Following crisis the reaction is no longer demonstrable. 2. Sera obtained from cases of pneumococcus pneumonia during illness and convalescence have been tested for antibodies specifically reactive with three chemically distinct constituents of Pneumococcus. The results, when correlated with the course of disease, demonstrate differences in the occurrence of each qualitatively distinct antibody. 3. The precipitation of pneumococcus Fraction C is not limited to the sera of individuals ill with pneumococcus infection. But in the few other cases available for comparative tests, definite reactions have been obtained only in streptococcus and staphylococcus infections and in acute rheumatic fever.

IMMUNOLOGICAL RELATIONSHIPS OF CELL CONSTITUENTS OF ENCAPSULATUS PNEUMONIAE (FRIEDLANDER'S BACILLUS)

1. The soluble specific substance of Friedländer's bacillus is non-antigenic when dissociated from the cell. It is different for each type and it is highly reactive in the corresponding anti-S serum. 2. The nucleoprotein is antigenic, induces the species or protein antibody which reacts with capsule-free cells and protein derived from all types. Antiprotein sera do not react with either the encapsulated cell or the polysaccharide derived from it, and they offer no protection against infection. 3. Anti-R and antiprotein sera are identical in their behavior. 4. The carbohydrate of Friedländer's bacillus is demonstrable in filtrates of actively growing cultures and in the blood and urine of infected animals. 5. The protein is demonstrable in filtrates of only old, disintegrating cultures.

ON THE ROLE OF CARBOHYDRATE HAPTENS IN BACTERIAL ANAPHYLAXIS

1. In passively sensitized animals bacterial anaphylaxis has been produced, in vivo and in vitro, with haptens from B. lactis aerogenes, the pneumobacillus, and a yeast. 2. The smallest amount of hapten causing fatal anaphylaxis is less than the minimal amount of protein which will cause death in properly sensitized animals. 3. The haptens used were largely carbohydrates, and gave none of the protein reactions, but since they did contain a small amount of nitrogen we cannot yet assert positively that carbohydrate alone will produce shock. 4. Since haptens will not sensitize animals we must conclude that the anaphylactogenic and shock-producing parts of the antigen are not identical. 5. These experiments provide further evidence of the close relationship of precipitins to anaphylaxis.

STUDIES IN AGGLUTINATION : III. ON THE MECHANISM OF THE AGGLUTINATION OF BACTERIA BY SPECIFIC AGGLUTINATING SERUM

From the foregoing evidence, specific bacterial agglutination may be conceived of as follows: When bacteria are mixed with their homologous agglutinative sera, specific union between organism and agglutinin occurs. This interaction consists of specific coating of the bacteria by globulin. By virtue of the fact, noted by Loeb and illustrated in Fig. 6, that protein film formation gives the coated particle the characteristics of denatured protein, the bacteria now take on the character of particles of denatured globulin. Particles of denatured protein flocculate whenever their charge is reduced by electrolyte to a critical level lying somewhere between 12 and 14 millivolts. This is true even when the salt is strong, as, unlike bacterial particles, their cohesive force is not readily depressed by salt. The sensitized bacteria, now being essentially particles of denatured protein, likewise agglutinate as soon as their charge is reduced by electrolyte to this potential level.

STUDIES ON THE ANTIGENIC SUBSTANCE OF THE BACTERIAL CELL

Putting together the results of such experiments as those outlined above, we can set down the following definite facts. 1. The substance of the bacterial cell can be roughly divided into two antigenic entities. One of these is the so called "nucleoprotein" substance, the other the residue substance or soluble material of Dochez and Avery and Avery and Heidelberger, both of which have been repeatedly characterized in preceding papers. 2. Immunization with the nucleoprotein, if such nucleoprotein is rendered free of bacterial bodies or fragments of bacterial bodies by Berkefeld filtration, incites the production only of antinucleoprotein antibodies which, with slight group overlapping, are species-specific but, as determined by the previous studies of Avery and, subsequently, those of Lancefield, are not type-specific to the same degree as the residue antibodies. 3. Immunization with dissolved residue alone leads to no antibody formation whatever. This residue, as indicated in several of our own previous studies, represents the haptophore group upon which specificity depends and which, in the simple process of solution, is disrupted from another substance together with which it represented a complete antigen in the antibody-forming sense. 4. The formation of specific antiresidue antibodies is apparently dependent upon the injection of morphologically formed elements, at least as far as experiment can determine at the present time; for, as in the pneumococcus experiments, the most available process of solution and the injection of all the materials so obtained from the whole bacteria fails to yield antiresidue antibodies, as though in the mere process of dissolving the residue haptophore group were dissociated from its association with the larger molecule to which, in the whole bacteria, it lends specificity. 5. While antiresidue antibodies are only formed when such undisrupted bacterial cell substances are present in the immunizing substance, immunization with whole bacteria, even when attempts are made to preserve them from solution by formalin, leads to the formation of both antiresidue and antinucleoprotein antibodies, probably because a certain amount of solution inevitably takes place after injection within the animal body.

THE IMMUNOLOGICAL RELATIONSHIPS OF STREPTOCOCCUS VIRIDANS AND CERTAIN OF ITS CHEMICAL FRACTIONS : II. SEROLOGICAL REACTIONS OBTAINED WITH ANTINUCLEOPROTEIN SERA

1. The immunological behavior of two cell constituents of nonhemolytic streptococci has been studied, (a) One, the so called nucleoprotein, is relatively non-specific and gives rise to an antibody which shows group reactions with nucleoproteins of related species. (b) The other is non-protein by qualitative chemical tests. Preliminary chemical examination has indicated that it may be a carbohydrate. Although this substance is highly reactive with the specific antibodies produced by the intact bacterial cell, yet in its chemically purified condition it is probably non-antigenic. Specific serological reactions with this substance are dosely related to specific agglutination of the microorganism. 2. The study of sera prepared by immunization with the chemically extracted protein has shown the presence of antibodies for nudeoproteins alone. No antibodies against the specific soluble substance have been found in these sera. The protein antibodies are little, if at all, concerned in causing agglutination. Precipitin tests, complement fixation reactions, and absorption experiments have been used to analyze the group relationships with the nucleoproteins of other species. The proteins of each species of Gram-positive cocci studied were immunologically similar within the species and showed definite relationships to the proteins from related species. Proteins from bacteria of unrelated species did not react with antisera against streptococcus protein. 3. Two distinct antibodies have been demonstrated in antisera prepared against living bacteria. By prolonged immunization it was found possible to produce sera with a high content of protein as well as specific antibodies. With ordinary methods, however, the immune sera had a low content of relatively non-specific protein antibodies but a high titer for specific antibodies. The specific antibodies were not reactive with proteins but were active with high dilutions of the soluble specific substance and were responsible for the parallel specific agglutination. Absorption experiments showed that the two antibodies in antibacterial sera were immunologically distinct.

CHEMICAL AND IMMUNOLOGICAL PROPERTIES OF A SPECIES-SPECIFIC CARBOHYDRATE OF PNEUMOCOCCI

Pneumococci contain a non-protein constituent which, on the basis of its chemical and immunological properties, appears to be a carbohydrate distinct from the type-specific carbohydrate and common to the species.

CLASSIFICATION OF THE HEMOLYTTC STREPTOCOCCI BY THE PRECIPITIN REACTION

A method is described for the preparation from hemolytic streptococci of extracts containing a soluble precipitating substance. By the use of such extracts, it is shown that nearly all members of this family yield a common precipitable substance. So far, therefore, as concerns the precipitin reaction, the hemolytic streptococci form a practically homogeneous group.

SOME OBSERVATIONS ON THE SPECIFICITY OF BACTERIAL ALLERGY TO CERTAIN OF THE NEISSERIAE

By means of the reaction to intracutaneous inoculation with bacterial suspensions in amounts of 0.2 cc., bacterial allergy was demonstrated in rabbits into which had been implanted agar foci containing either gonococci, meningococci, M. catarrhalis, or Bact. lepisepticum. The criterion of hypersensitiveness was the relative size and intensity of reaction evoked by an identical dose in "agar focus" and control rabbits. Rabbits sensitized to gonococci or meningococci usually reacted indistinguishably to either of these organisms, but were less allergic to M. catarrhalis. Similarly, animals sensitized to M. catarrhalis gave moderate but not maximal responses to the two former organisms. Cross-reactions did not occur between Bact. lepisepticum and any of the three Neisseriae. Animals sensitized to the four organisms mentioned reacted no more intensely than did controls to hemolytic streptococci, staphylococci, and rough pneumococci. The hypersensitive state was found to begin early in the 2nd week and to end usually by the 4th week, being at its height in most instances on the 10th to 12th days. The number of organisms contained in the agar focus determined the success of the sensitization only to this extent, that very small and very large inocula failed to evoke the allergic state. Rabbits immunized by intravenous injection of live organisms developed cutaneous reactions indistinguishable from those in controls. The "secondary rise" of Andrewes, Derick, and Swift was rarely observed.

SPECIFIC POLYSACCHARIDES FROM FUNGI

From each of five yeast-like fungi and a trichophyton there has been prepared a fraction which appears to be essentially a polysaccharide. Tested by direct precipitation against the corresponding antisera the polysaccharides from the yeast-like fungi exhibit only partial specificity. Cross-precipitin reactions are frequent. By absorption of precipitin on the intact mycotic bodies, however, a relatively high degree of specific precipitability can be demonstrated for the polysaccharides.

IMMUNOLOGICAL RELATIONSHIPS OF CELL CONSTITUENTS OF PNEUMOCOCCUS : SECOND PAPER

In this paper the general immunological significance of the intact pneumococcus cell and of its protein and carbohydrate components is discussed.

THE QUESTION OF SENSITIZATION OF JOINTS WITH NON-HEMOLYTIC STREPTOCOCCI

It was impossible to demonstrate a condition of specific joint sensitization to non-hemolytic streptococci by first injecting the joints of rabbits with small doses of killed non-hemolytic streptococci, or with extracts of these organisms, and subsequently inoculating the rabbits intravenously with homologous living bacteria. Joints so treated were no more liable to involvement than were other untreated joints of the same animals.

SEROLOGICAL REACTIONS WITH SIMPLE CHEMICAL COMPOUNDS (PRECIPITIN REACTIONS)

Experiments are described demonstrating the precipitation of azodyes by immune sera prepared by the injection of azoproteins containing the same azo component. These precipitin reactions prove conclusively the view already advanced on the basis of inhibition reactions that antibodies combine specifically with substances of small molecular weight. Although in this respect both phenomena have the same significance, the precipitin reactions with dyes are simpler in that the aid of a protein antigen is eliminated. That specific serological precipitin reactions can take place with substances other than proteins has been amply demonstrated by studies on bacterial antigens (14) (polysaccharides (15)). The present findings show that for the precipitation with immune sera not even a high molecular weight of the reactive substance is required. Factors determining the tendency to separate out from the liquid upon combination with antibody seem to be the colloidal state of the solution and the chemical composition of the substance. With regard to the influence of chemical composition, a striking example is provided by the suberic acid dye which gives particularly strong precipitin reactions, most probably on account of its long aliphatic side chains. The results reported may be of use for studies on the mechanism of serological precipitation.

THE ANTIGENIC PROPERTIES OF SOLUTIONS OF PNEUMOCOCCUS

1. Intact pneumococci, possessing specific antigenic powers unimpaired by cultural or other procedures, give rise to agglutinins for organisms of the homologous type and to precipitins for the type-specific carbohydrate derived from them. 2. Solutions of pneumococci free of all formed elements, but containing the carbohydrate and protein of the original cell, fail to stimulate the formation of type-specific antibodies. Sera prepared in this manner do not react with the carbohydrate constituent of the cell and do not agglutinate organisms of the homologous type. The loss of this antigenic function is related to changes incurred during dissolution of the bacterial cell. 3. Solutions of the cellular substances of Pneumococcus, although lacking the specific antigen of the whole cell, induce the formation of antibodies reactive with pneumococcus protein regardless of the type from which the latter is derived.

STUDIES ON MENINGOCOCCUS INFECTION : III. THE ANTIGENIC COMPLEX OF THE MENINGOCOCCUS-A TYPE-SPECIFIC SUBSTANCE

Three fractions have been isolated from autolysates of the meningococcus. Of these, one, the type-specific substance, has been described in detail. The same type-specific substance appears to be present in Type I and Type III organisms, but a substance differing at least serologically has been obtained from Type II strains. Detailed chemical analysis of both of the type-specific substances thus far isolated is being carried out and will be the subject of a later paper.

AN EXPERIMENTAL ANALYSIS OF BACTERIAL ALLERGY

Our experiments have confirmed the fact that the so called bacterial allergies are dependent upon a mechanism which differs materially from that determining true protein anaphylaxis. Anaphylaxis to protein substances of the bacteria probably occurs but plays a relatively unimportant rôle in the phenomena of infection. The bacterial allergies, however, are of great importance since they develop rapidly and render the infected animal highly vulnerable to products of the bacterial growth which are relatively innocuous for the normal animal. Neither the type-specific carbohydrate "residue antigens" (the "soluble specific substances" of Avery and Heidelberger) nor the antibodies reacting with them play any part whatever in bacterial allergy, and since these type-specific substances represent the haptophore groups of the whole bacteria by which they react with the agglutinins, precipitins, sensitizers, etc., of immune serum, allergy, as previously determined by Mackenzie and Woo, is in no way related to that phase of resistance which is determined by these antibodies. This does not, however, preclude the possibility that allergic hypersusceptibility may not in some way be related to other factors of resistance more definitely associated with cellular rather than with intravascular reactions. Our previous studies with Jennings and Ward in tuberculosis point in this direction (20). Guinea pigs can be actively sensitized with all the bacteria with which we have worked when repeated injections of whole bacteria or of the protein (nucleoprotein) fraction are administered. Large amounts of the latter are necessary since these materials are indifferent antigens, possibly because of the severe manipulations necessary in their production. Sensitiveness develops usually within 10 days after the first dose and increases with continued treatment for 3 or 4 weeks. Sensitiveness is relatively specific, by which we mean that there is a definite specificity which, however, in highly sensitive animals is not absolute and shows considerable overlapping. Continued treatment with considerable quantities of the above substances leads to gradual desensitization in animals in which there are no chronic foci present, which, as in tuberculosis, tends to continue the sensitization. Attempts at passive sensitization have been irregular and inconclusive. When any degree of sensitiveness has developed after the injection of immune sera, it has appeared late and has been of doubtful specificity. Conversely we have failed in any case to neutralize the activity of the active allergic constituents of bacterial extracts by incubation with any type of immune serum. We have failed so far to show any increased fixation of tuberculin material on the part of tuberculous tissues or on that of living tuberculous animals. These failures, however, seem to us of relatively slight importance since quantitative experiments of this nature are extremely difficult in the case of a substance as delicately potent for the tuberculous animal. On the other hand we have obtained definite, though irregular evidence that the incubation of O.T. with fragments of tuberculous lung tissue (less clearly with other tissues) leads to the formation of a substance that produces allergy-like lesions in the skin of normal guinea pigs. With somewhat greater regularity, similar treatment of O.T. has enhanced the potency of the tuberculin for tuberculous animals. And, in these experiments there was evidence that the factor responsible for this action was not easily separable from the cells themselves. When these experimental data are analytically considered they appear in many respects confusing and contradictory. There has been so much work done on the tuberculin reaction, moreover, that, in the face of experimental inconsistencies it would seem foolhardy to formulate more than tentative suggestions to explain the mechanism of these reactions. Nevertheless there are a few outstanding and sufficiently reliable facts which compel a limited number of definite deductions. In the first place there is no question of the complete independence of the true allergic phenomena from the ordinary bacterial antigen-antibody reactions. We know, moreover, that the allergic substance is chemically separable from the carbohydrate "residue" or haptophore group of the bacteria (Mueller, Laidlaw and Dudley). Indeed it has been shown by Long and Seibert (21) that the active allergic substance is either a protein in itself, or at any rate closely associated with the bacterial protein. Furthermore, the distinct, though limited, specificity of the allergic sensitiveness compels the conclusion that we are dealing with an immunological process in which the tissue cells acquire an increased specific capacity to react with this nitrogenous material, a capacity which, in principle, is not far removed from the supposed "sessile receptor" apparatus which is conventionally held responsible for protein anaphylaxis; and this analogy is further amplified by the apparent desensitization which continued treatment produced in many of our own experiments as well as in those of Mackenzie and Woo. Here, however, the analogy with protein anaphylaxis ends. Passive sensitization with any form of immune serum or with the sera of highly sensitized animals is either feeble or entirely unsuccessful and indicates quite convincingly that, whatever the receptor apparatus of the cells may be, it is not easily given up to the blood stream as are ordinary antibodies. Further than this, our tissue-tuberculin experiments, irregular and occasional as they were, nevertheless convinced us that: 1. The contact with the tissues of tuberculous animals results in the production of a toxic factor, not unlike the autolytic toxic materials of some bacteria. 2. The active cell constituent by which this action is wrought, is not easily separated from the cells, even by energetic methods of extraction. This close association of the entire process with the cells themselves is particularly significant in view of the obvious cell injury in which these delayed allergic effects differ from the ordinary urticarial, evanescent reactions associated with protein anaphylaxis. The process of allergy, as far as we can approach it then, may be conceived as follows: A nitrogenous, probably protein, constituent of the bacterial growth or of its body substance stimulates a specific reaction in the tissue cell by which its specific capacity to establish contact with this constituent is enhanced. The cell is thereby enabled to exert a, probably, enzyme-like effect upon this material in consequence of which a toxic substance is liberated, largely upon or possibly within the cell itself. Both processes may be dependent upon one and the same reaction body. But it seems more likely that increased contact and the increased cell activity are separately developed, an assumption which is rendered probable by the association of the highest degrees of allergy with inflammatory cell reactions, and by the fact that moderate and less specific allergic sensitiveness follows 10 or more days after the administration of considerable amounts of indifferent protein substances to guinea pigs. We interpret this as signifying that such injections may non-speciffcally increase cellular activity, a change which many earlier workers have spoken of as "cell irritability." Both processes are closely associated with the altered cell itself and the factors by which the reaction is brought about are not easily given up to the blood stream as are the antibodies formed in response to injections of proteins or whole bacteria. We are confronted, therefore, with an immunological mechanism which has some close analogies to those others in which circulating antibodies are formed, but which differs from these mainly in the intimacy with which the entire reacting system is associated with the cells themselves. It is difficult to conceive that a functional cell alteration, as profound as this, should be entirely unrelated to the phenomena of susceptibility or resistance.

THE IMMUNOLOGICAL RELATIONSHIPS OF STREPTOCOCCUS VIRIDANS AND CERTAIN OF ITS CHEMICAL FRACTIONS : I. SEROLOGICAL REACTIONS OBTAINED WITH ANTIBACTERIAL SERA

1. Agglutination and precipitation by the specific substance of Streptococcus viridans are parallel phenomena. Separate specific substances have been extracted from strains which are distinct by ordinary serological tests. Preliminary chemical examination indicates that the specific substances may be complex carbohydrates. 2. A close relationship between nucleoproteins from different strains of Streptococcus viridans is suggested by the existence of a certain amount of cross-precipitation and a larger degree of cross-complement fixation. But the occurrence of stronger reactions with homologous nucleoproteins than with heterologous indicates that there is some degree of individual difference in proteins from separate strains. 3. Two distinct antibodies are present in the sera antibacterial for Streptococcus viridans: one of high titer implicated in the parallel phenomena of agglutination and precipitation by the soluble specific substance, the other usually of low titer and involved in precipitation by nucleoproteins but probably little, if at all, in agglutination. The significance of these results obtained from the study of antibacterial sera will be considered in the general discussion of the antigenic components of Streptococcus viridans after the results from the study of antinucleoprotein sera have been presented in the succeeding paper.

PRECIPITATION AND COMPLEMENT FIXATION REACTIONS WITH RESIDUE ANTIGENS IN THE NON-HEMOLYTIC STREPTOCOCCUS GROUP

The applicability to the non-hemolytic streptococci of the technique used for the extraction of a soluble precipitating substance from the hemolytic streptococci is demonstrated. With this substance as antigen, it is demonstrated by means of precipitation and complement fixation that the non-hemolytic streptococci form an antigenically distinct, but entirely heterogeneous group. Such cross-reactions as do occur within this group are not useful in the systematic classification of these organisms.

STUDIES ON PNEUMOCOCCUS IMMUNITY : III. THE NATURE OF PNEUMOCOCCUS ANTIGEN

1. Active immunity against many lethal doses of Pneumococcus Types I, II, and III may be produced in mice by two or three subcutaneous injections of the homologous type of pneumococcus saline vaccine. 2. Mice may be actively immunized with the protein fraction obtained by treating pneumococci with anhydrous sodium sulfate or by solution of pneumococci in bile salts and precipitation with alcohol. Pneumococcus antigen is therefore carried within or adheres to the protein fraction of the organism. 3. Pneumococcus antigen is resistant to prolonged autolysis and to tryptic digestion, and can be recovered from the soluble portions of digests of either the intact bacteria or the bacterial protein. 4. The antigen may be isolated from each of the three fixed types of pneumococcus by tryptic digestion of the pneumococci and extraction of the digest with 70 to 90 per cent alcohol. The antigen is not soluble in absolute alcohol, nor is it soluble in ether or in the other lipoidal solvents. 5. The immunizing property of slightly acid solutions of the antigen is not impaired by boiling for 5 minutes, nor by heating at 56°C. for 1 hour. Sterile unpreserved solutions of the antigen did not deteriorate by standing in the refrigerator for 3½ months. 6. The exact chemical nature of pneumococcus antigen still remains to be determined. From the experiments reported it appears that the antigen is non-lipoidal, that it probably adheres to the protein fraction in a loose chemical or physical union rather than representing a protein complex of a large molecular size, as shown by its solubility in alcohol, its thermostability, and its resistance to proteolytic digestion. 7. Some of the antigens studied have been shown to contain a non-specific factor promoting the growth of bacteria. 8. The purified pneumococcus antigen solutions are non-toxic for mice.

THE SOLUBLE SPECIFIC SUBSTANCE OF PNEUMOCOCCUS

1. A method is given for the concentration and purification of the soluble specific substance of the pneumococcus. 2. The material obtained by this method is shown to consist mainly of a carbohydrate which appears to be a polysaccharide built up of glucose molecules. 3. Whether the soluble specific substance is actually the polysaccharide, or occurs merely associated with it, is still undecided, although the evidence points in the direction of the former possibility.

STUDIES ON PATHOGENIC B. COLI FROM BOVINE SOURCES : IV. A BIOCHEMICAL STUDY OF THE CAPSULAR SUBSTANCE

1. The soluble specific substance obtained from a capsulated strain of B. coli is not identical with any specific substance heretofore described. It is a carbohydrate, composed of 80 per cent of hexose, probably partly of dextro- and partly of levorotatory sugar, since the rotation of the hydrolysate is low. Glucuronic acid is probably present in the molecule. 2. Crude "residue" or specific substance obtained from the uncapsulated mutant was about 100 times less active with homologous serum than similar material from the capsulated strain. This supports the view that capsular substance and soluble specific substance are the same. In cases where there is a well marked capsule, the specific substance is probably produced in greater amount and located peripherally. 3. Capsular substance is probably significant for virulence when functioning as a morphological capsule. It is present in filtrates of young culture only in very small amounts.

A SPECIFIC FLOCCULATION REACTION OCCURRING BETWEEN ALCOHOLIC EXTRACTS OF PNEUMOCOCCI AND ANTIPNEUMOCOCCUS SERUM

1. A flocculation reaction has been described which occurs between alcoholic extracts of pneumococci and antipneumococcus serum. 2. The reaction appears to be species-specific. It is not strictly type-specific, as slight or moderate cross-reactions occurred between Type I serums and Type II and Type III extracts. 3. The flocculating power of the serum from five horses undergoing immunization with pneumococcus, Type I, did not develop to any extent before the end of the 4th or 5th month. 4. In the case of two of these horses in which it was possible to carry out parallel tests on a larger number of subsequent bleedings until the end of immunization, some relationship was suggested between the flocculating power and the protective titer as ascertained by the routine method of standardization in mice.

ON THE NATURE OF BACTERIAL ALLERGIES

1. There seems no further possibility of questioning the opinion that the development of tuberculin sensitiveness is definitely associated with the development of tissue reactions in the form of inflammatory processes; the mere development of antibodies on the injection of dissolved bacterial materials does not induce allergy. 2. Passive transfer of tuberculin allergy to guinea pigs may be accomplished by injections not only of the tissue extracts of the tuberculous foci of rabbits, but also of the sera of such rabbits, provided multiple, well developed, and not too advanced lesions are present in the rabbits furnishing them. The exact criteria by which such results can be regularly obtained have not yet been ascertained; our results in this respect, though definite, have been irregular and occasional. It is clear, moreover, that the capacity to convey such allergic hypersensitiveness has no relationship to the precipitating capacity of the serum for residue materials. 3. Just as the allergy-conveying power of the serum and its precipitating powers for residue are separable, so, also, the bacterial extracts representing the antigens for these reactions are separable, the residue material being particularly concerned in the specific precipitations with immune serum, the so called nucleoprotein being associated with allergic reactions in the tuberculous animals.

IMMUNOLOGICAL PROPERTIES OF A TYPICAL (S-PRODUCING) AND A DEGRADED (NON-S-PRODUCING) STRAIN OF TYPE II PNEUMOCOCCUS WITH SPECIAL REFERENCE TO PROTECTIVE ANTIBODIES

The loss of the specialized function of S production by Type II pneumococcus was accompanied by a loss of the antigenic properties involved in both active and passive protection of mice. Absorption of Type II serum with S-producing pneumococci removed all the protective antibodies, as well as the type-specific agglutinins and S precipitins. The same absorption treatment of the serum by non-S-producing pneumococci failed entirely to remove the type-specific antibodies and did not affect the protective value of the serum. Absorption with bacteria-free culture fluids containing the reactive carbohydrate removed the protective antibodies as completely as absorption with the whole bacterial cells of type-specific strains. The results taken as a whole indicate that the antibodies involved in the usual protection of mice against Type II pneumococci are closely related, if not identical, to the specific anticarbohydrate precipitin.

THE ANTIGENIC COMPLEX OF STREPTOCOCCUS HAEMOLYTICUS : I. DEMONSTRATION OF A TYPE-SPECIFIC SUBSTANCE IN EXTRACTS OF STREPTOCOCCUS HAEMOLYTICUS

1. Hydrochloric acid extracts of Streptococcus haemolyticus contain type-specific, as well as non-type-specific, substances. The precipitates formed by these crude extracts with homologous antibacterial serum are flocculent, while those obtained with heterologous serum are usually disc-like. 2. The type-specific substance may be detected by the use of anti-bacterial sera absorbed with heterologous strains of hemolytic streptococci. Such absorbed sera are type-specific: they are precipitated only by extracts of strains of the homologous type. 3. Any heterologous strain of hemolytic streptococcus absorbs the antibodies for all other heterologous strains, but homologous strains absorb type-specific antibodies as well. Numerous repeated absorptions with heterologous hemolytic streptococci tend to lower the titer of the type-specific antibody. A possible explanation of this fact is suggested. 4. Three strains did not yield a type-specific substance; and it seems probable that they had lost this function because of long continued cultivation in artificial media. 5. Classification based on the precipitin test with absorbed serum agrees with that previously determined by agglutination and protection tests. The method is, therefore, applicable to the problem of classification of the hemolytic streptococci.

THE SIGNIFICANCE OF ANAPHYLAXIS IN PNEUMOCOCCUS IMMUNITY

1. Intraperitoneal injections of killed and living broth cultures of a virulent pneumococcus produce in guinea pigs a high degree of active immunity and a serum with strong protective power. 2. Despite the protective power of such serum no agglutinins for the homologous organism and no precipitins for soluble derivatives were demonstrable. 3. Guinea pig immunity to pneumococcus infection produced by the method described is not attended by cutaneous allergy to derivatives of the pneumococcus used for immunization. 4. During the course of an artificially produced active immunity, anaphylaxis may at times be present and at times absent without any measurable effect upon the resistance of the animal to infection by intraperitoneal injection. 5. In the particular instance studied, the experiments indicate that anaphylaxis to pneumococcus protein has no important effect upon the resistance of the animal to infection. It appears to be a concomitant without any significant rôle in the immunity mechanism.

ON PRECIPITABLE SUBSTANCES DERIVED FROM BACILLUS TYPHOSUS AND BACILLUS PARATYPHOSUS B

Attempts to confirm certain statements that ether-soluble specific substances can be obtained from B. typhosus have lead to negative results. Two serologically active protein substances and another that was non-protein have been separated from B. typhosus. The first two are not resistant to tryptic digestion or to treatment with alkaline hypochlorite solution whereas the third resists both. One of the proteins could be extracted with 75 per cent alcohol. Specific precipitable substances reacting like the non-protein substance of B. typhosus and containing large amounts of carbohydrates have been prepared from B. paratyphosus B, B. enteritidis, and Proteus HX19 and OX19. Observations on the serological behaviour of these preparations are described.

THE CARBOHYDRATES OF GONOCOCCUS AND MENINGOCOCCUS : I. THE ALCOHOL-PRECIPITABLE FRACTION

The alcohol-insoluble polysaccharides of gonococcus and meningococcus were found to contain 4.2 and 3.7 per cent nitrogen respectively, to be protein-free by chemical test, to reduce FehIing-Benedict solution only after hydrolysis. They were non-toxic for rabbits and mice, and failed to engender antibodies (precipitins) in rabbits. They produced no cutaneous reactions in normal, snuffle-free rabbits, but caused typical allergic reactions of the delayed type in rabbits rendered hypersensitive to these organisms. Both carbohydrates reacted in high dilution with Antipneumococcus Serum Type III. For comparison, carbohydrates were prepared also from Micrococcus catarrhalis, Streptococcus hemolyticus, Staphylococcus aureus, and a rough strain of pneumococcus.

PRODUCTION OF HETEROGENETIC ANTIBODIES WITH MIXTURES OF THE BINDING PART OF THE ANTIGEN AND PROTEIN

1. The alcohol-soluble extract of heterogenetic antigen, which possesses the specific chemical structure of the entire antigen, has a detectable but generally very slight power to increase the amount of heterogenetic antibodies, when injected into rabbits. 2. This substance can be transformed into an efficient antigen by mixing it with protein solutions such as diluted normal serum. 3. Such mixtures are considerably more active than the same substances injected separately. Therefore, the effect of the serum is probably due to the formation in vitro of a loose compound between the alcohol-soluble substance and protein, the compound acting as a complete antigen. 4. It may be supposed that there exists a group of natural antigens which are built up of one specifically reacting part that is almost or entirely devoid of antigenic properties, and another part, a protein, responsible for the immunizing effect.

Correlations between plasma protein fractions, antibody titers, and the passive transfer of delayed and immediate cutaneous reactivity to tuberculin PPD and tuberculopolysaccharides

GUINEA PIGS SENSITIZED WITH TUBERCLE BACILLI DEMONSTRATE A DUAL ALLERGIC RESPONSE MEDIATED BY TWO CHEMICALLY DISTINCT PLASMA FRACTIONS: 1. Antibody to tuberculopolysaccharide is located exclusively in fraction II (gamma globulin). This fraction will passively transfer systemic anaphylaxis and urticarial type skin reactivity to tuberculopolysaccharide, and contains the Middlebrook-Dubos antibody. 2. Antibody to tuberculoprotein is contained exclusively in a new plasma fraction called fraction IV-10. By Cohn's Method X, fraction IV-10 is a part of fraction IV (alpha globulin) and to a lesser extent V (albumin). This fraction will passively transfer to normal guinea pigs a delayed type skin sensitivity to tuberculin PPD which is maximal between 18 and 30 hours, and it contains the Boyden antibody. When fractions II and IV-10 are combined, the antibody to tuberculopolysaccharide inhibits the passive transfer of delayed type reactivity. Combination of these two fractions does not alter their separate in vitro hemagglutinating properties. Adsorption of IV-10 with Boyden sensitized cells removes its ability to transfer delayed type tuberculin sensitivity. Adsorption of II with Middlebrook-Dubos-sensitized cells removes its capacity to effect passive transfer of immediate type reactivity to tuberculopolysaccharides.

Bacterial proteins.—The presence of alcohol-soluble proteins

In the course of an investigation of the Gram-staining material in Strepto­cocci and Staphylococci, substances giving the general reactions of the alcohol-soluble proteins or gliadins have been isolated. Alcohol-soluble proteins, or prolamins (Osborne (1)), are especially characteristic of the seeds of cereals; among them gliadin of wheat and rye, hordein of barley, and zein of maize are typical examples. The present communication deals with the alcohol-soluble fraction of bacterial protein: the other soluble protein substances will form the subject of a later communication. The work was commenced in 1917 as part of the author’s study of war wounds, but had to be abandoned, and was not recommenced until the winter of 1923. Most investigations on bacterial proteins have been conducted by extracting the bacterial cells with alkaline solutions, with or without heating; such a pro­cedure is likely to modify certain of the proteins, and, as will be seen later, would entirely remove the alcohol-soluble fraction. Bacteria are especially resistant to the solvent action of the majority of biochemical solvents used for the extraction of proteins. The Gram-positive organisms, with the exception of Pneumococci, which are soluble in bile (Heidelberger and Avery (2) used this method in examining the protein of Pneumo­cocci) are especially refractory. Douglas and Fleming (3) extracted Staphylo­cocci with hot acetone and removed the Gram-reacting substance; Dreyer (4) used acetone and boiling formalin. All these processes are likely to alter the residual proteins. Liquid cultures are also unsatisfactory, are bulky to manipulate, and introduce disturbing factors.

Strain dependent variation of delayed-type hypersensitivity in Salmonella typhimurium infected mice

Inherently hypersusceptible C3H/HeJ and C3HeB/FeJ mice show increased resistance to challenge with virulent S. typhimurium after immunization with a live, avirulent S. typhimurium mutant in the absence of a delayed-type hypersensitivity response, while innately resistant C3H/HeNCr1BR and CD-1 mice show both immunity and positive footpad reactions after immunization. Understanding the mechanism for this specific anergy in the hypersusceptible strains may provide clues for understanding the immune defect that causes these mice to be so exquisitely susceptible to Salmonella infection.

Cellular antimicrobial immunity

Acquired resistance to infectious disease may be expressed by a predominantly humoral or a cellular mechanism or, more frequently, by a combination of the two. The cellular interactions which are responsible for the induction of the immune response in the skin, lung, intestinal mucosa, genitourinary tract, conjunctiva, and peritoneal cavity are discussed and the role of living or dead vaccines in the induction of acquired resistance is outlined. The host response involves three different cell types: the phagocytic cell (polymorphs or macrophages), the thymus-dependent (T) lymphocyte, and the thymus-independent (B) lymphocyte-plasma cell line. The normal unstimulated phagocytic cell is capable of killing most nonpathogenic bacteria that gain entry to the tissues. However, the presence of opsonic antibodies and activated macrophages is required to eliminate the pathogenic intracellular parasites. Such immunological activation involves the presence of sensitized T-lymphocytes in the lesion. The cellular response is also characterized by the simultaneous development of a state of delayed-type hypersensitivity (DTH), along with the antimicrobial CMI response. A rising humoral response normally develops subsequently. Killed bacterial cells (except when incorporated into Freund's complete adjuvant) induce the humoral response without the CMI reaction so that such vaccines are not able to fully protect the host against the naturally acquired disease. With the development of cell fractionation methods as well as the identification of distinctive cell surface markers, suspensions of B- and T-cells and macrophages can now be prepared for use in increasingly sophisticated transfer and reconstitution studies. The role of the different cell types in the expression of humoral and cellular immunity has been determined, and the effect of various immunopotentiating and immunosuppressive regimens on the immune system as a whole has been evaluated quantitatively. These studies have led to an appreciation of the role played by suppressor B- and T-cells in the interplay of both humoral and cellular components of the host defense system during the development of immune tolerance, desensitization, anergy, autoimmunity, and the expression of an anamnestic immune response following reinfection.

A method for coupling protein antigens to erythrocytes. I. Description of method

A technique has been described whereby tuberculin PPD is coupled, via tetrazotized benzidne, onto the surfaces of formalinized red blood cells. A stable antigen preparation is thereby obtained, which may be stored at -40 degrees C. The purpose of the present method is to facilitate the study of antibody to tuberculoprotein.