Antituberculous immunity induced by methanol extracts of tubercle bacilli; its enhancement by adjuvants

Studies on fractions of methanol extracts of tubercle bacilli. I. Fractions which increase resistance to infection

Fractionation procedures yielding partially purified vaccine preparations from a 60°C. methanol extract of tubercle bacilli have been described. Some of the preparations have the characteristics of lipopolysaccharides. Certain ones have been found capable of increasing resistance to experimental tuberculosis in albino mice of the Rockefeller Swiss strain. The levels of resistance elicited by these preparations are equivalent to those following vaccination with BCG (Phipps) in this strain of mice as reported by other authors. The admixture of two of the crude fractions in amounts as small as 0.05 mg. each per dose per mouse affords an even greater increase in resistance. Neither of these substances alone in larger doses can approach this degree of efficacy in mouse protection experiments. The protective activity appears to involve the stimulation of two supplementary mechanisms, one providing a peak resistance between 1 and 3 weeks post vaccination but falling off to a lower level thereafter, the other not responding fully until approximately 6 weeks but continuing undiminished through a 12 week post-vaccination period. The first of these peaks corresponds to an increase in resistance against staphylococci as well as tubercle bacilli. The possibility that the term "broad specificity," rather than "non-specificity," might best describe this phenomenon permits the implication of classical immune mechanisms.

Lysed BCG vaccines. 1. Observations on optimal conditions for BCG growth and lysis

As a first step towards the production of a lysed BCG vaccine that would have reduced toxicity and allergenicity and yet be immunogenic, the growth and lysis of BCG bacilli under strictly controlled conditions have been studied.BCG grown in both Dubos and Aldridge liquid media showed an arithmetic linear growth, preceded by a very short logarithmic phase. This suggested that some of the cell population became metabolically inactive at a very early stage, possibly owing to suboptimal conditions of growth.Glycine, lysozyme and lithium chloride initiated lysis of BCG growth in the aforementioned media 24-48 hours after inoculation. After 2 weeks' incubation approximately 50% of the original BCG culture was lysed and the viable count had fallen 1000-fold. The autolytic pattern of BCG in a nitrogen-deficient, chemically defined Aldridge medium is also described.

The adjuvant activity of aliphatic nitrogenous bases

By the use of diphtheria toxoid in guinea-pigs, high adjuvant activity has been found in a number of aliphatic nitrogenous bases including amines, quaternary ammonium compounds, guanidines, benzamidines and thiouroniums. Activity appears to depend on a combination of basicity and a long aliphatic chain of twelve or more carbon atoms. Such adjuvants tend to be haemolytic, and cause damage to tissue culture monolayers. It is suggested that their activity is connected with their surface activity and hence their ability to alter cell membranes, but that the basicity plays a further as yet undetermined role.

Some biological properties of BCG after the extraction of lipids: the power to irritate tissues, the ability to prepare for and to evoke Bail's phenomenon, and the power to sensitize to tuberculin

Mycobacterium tuberculosis var. bovis BCG was treated with lipid solvents according to Macheboeuf's method and five progressively more fully extracted bacillary residues were obtained. Electron-microscope examination, together with the biological properties studied, showed that a major transformation was brought about in the bacillary residues by methanol extraction. The biological properties of the residues were studied quantitatively in guinea pigs. The power to irritate tissues (i.e., to produce tuberculous-like lesions in tissues), the ability to prepare for and to evoke Bail's phenomenon (i.e., reaction to the intraperitoneal introduction of bacillary bodies in a sensitized guinea pig characterized by an immediate leucocytic response and death within a few hours), and the power to sensitize to tuberculin were directly proportional to the lipid contents of the bacillary bodies and decreased as the extraction progressed. The residues with the lower lipid contents were less irritant, less sensitizing, and less reactive. However, these properties never completely disappeared. The role of the lipids as related to the above properties of mycobacteria was thus indirectly established. With the doses and the routes of injection used, no obvious toxic effects in normal guinea pig were observed.

THE EFFECT OF BACTERIAL CONSTITUENTS ON THE RESISTANCE OF MICE TO HETEROLOGOUS INFECTION AND ON THE ACTIVITY OF THEIR RETICULO-ENDOTHELIAL SYSTEM

Administration of small amounts of salmonella endotoxin (20 microg.) or of acetone-extracted BCG cells (100 microg.) increases the resistance of mice to infection with Myco. fortuitum as well as their ability to clear carbon particles from their blood stream. Whereas the increased resistance to infection persists for many weeks, the clearing power returns to a normal level within a few days. When normal mice are infected with Myco. fortuitum, there occurs during the first phase of the infectious process a rise in clearing power for carbon particles followed by a fall during the terminal phase of the disease. The rise occurs more rapidly and is more pronounced in animals previously treated with salmonella endotoxin or with killed BCG cells. This acceleration and intensification of the phagocytic response to infection can be detected even in animals which exhibit a normal phagocytic index when tested several weeks after administration of endotoxin or of BCG. Although increase in resistance to infection is correlated with activation of the so called reticulo-endothelial system, there is no evidence of any direct causal relationship between the two phenomena.

Effects of cellular constituents of mycobacteria on the resistance of mice to heterologous infections I. Protective effects

Vaccination with living attenuated tubercle bacilli (BCG) was found to increase the resistance of mice to infection with virulent staphylococci. An even more striking protective effect could be elicited by intraperitoneal or subcutaneous injection of small amounts (0.1 mg. or more) of killed BCG cells. The killed BCG cells retained most of their protective activity after prolonged heating at acid, neutral, or basic reactions-and after extraction with acetone, methanol, and NaOH (at pH 10.5). Some protective activity could be recovered in a fraction soluble in methanol at 55 degrees C. The protective effect against infection manifested itself in a prolongation of survival time following infection, and also in the fact that smaller numbers of staphylococci were recovered from the organs of infected mice. Both types of effects were still evident 10 weeks after vaccination. Injection by the intraperitoneal route of killed cells of BCG, or of methanol extracts of them, elicited in mice a high level of protection against intravenous injection of Myco. fortuitum. A protective effect quantitatively and qualitatively similar to that elicited by BCG, resulted from the intraperitoneal or subcutaneous injection of killed cells of Myco. fortuitum.