Julia T. Parker

The antigenic properties of ragweed pollen

Although most of the evidence would lead one to believe that pollens are antigenic, there are a few experimenters who still hold to a contrary opinion because they have been unable to produce antibodies to pollens. The question is of interest in its relation to hay fever. If pollens are antigenic, the anaphylactic nature of hay fever may be regarded as at least a possible explanation of the phenomenon. As pollens contain protein, although in small amounts, it would naturally be assumed that when sufficiently large quantities of pollen have been injected and delicate enough tests performed, antibodies could be shown to be present. Although we have only two experiments to report, our results are so convincing that we feel that a definite conclusion is justifiable. These results were obtained by testing the isolated uteri of sensitized guinea pigs by the Dale Method.

Further studies on the production of staphylococcus aureus toxin.

In a previous paper 1 we showed that certain strains of Staphylococcus aureus produce an exotoxin which causes necrosis when injected intradermally into rabbits. With the methods used at that time only 8 out of 118 strains from pathogenic sources produced a toxin of sufficient strength to be demonstrable by this method. Recently, however, by two improvements in method, it has been possible to obtain the toxin from 13 out of 14 strains. These changes were: first, the growth of the staphylococcus culture in an atmosphere containing 10 per cent carbon dioxide and, second, the use of “Proteose peptone”∗ instead of Witte peptone in the broth media. For cultivation in the presence of CO2, the method of Cohen and Fleming 2 was used. The stronger toxin production in this atmosphere may be due to the fact that the pH of the broth cultures does not rise above 7.6 even after 8 days growth. When grown under the usual atmospheric conditions, even after 3 or 4 days growth, the staphylococcus cultures have a pH of 8 or over. There appeared to be some variation in different strains, but a strong toxin was produced most regularly when “proteose peptone” was used. In the production of other bacterial toxins it was found the amount produced by the staphylococcus varied greatly when different commercial brands of peptone were used in the medium. The table is given to show the amount of toxin which seven different strains of staphylococcus aureus produced on media prepared in exactly the same way, except for the presence of 6 different peptones. All of the cultures were grown in the same jar with 10 per cent carbon dioxide at 37° for 3 days.

On certain poisonous substances produced in bacterial cultures

In a paper published by one of us last year we called attention to the fact that it was quite likely that not all the toxic substances produced in cultures by bacteria can be peremptorily classified as either exotoxins or endotoxins. The writers working with a number of different organisms, biologically unrelated, have found poisonous substances of moderate potency developed both on fluid and on solid media which they believe should not be regarded at the present time either as specific or antigenic exotoxins, or as endotoxins. Indeed, it seems quite impossible at the present time to definitely classify these substances, for which reason they are referred to in our laboratory, for the present, as the “X” substances.

The production of an exotoxin by certain strains of staphylococcus aureus.

We have succeeded in demonstrating in sterile filtrates of broth cultures of four out of twenty-one strains of staphylococcus aureus isolated from various conditions, a powerful poison with a selective action for the skin. The poison is produced by the growth of these strains in any well buffered broth medium containing only a small amount of glucose. The medium from which our most powerful poisons were obtained was prepared by adding an equal volume of M/15 phosphate buffer solution pH 7.4 to ordinary sugar—free meat infusion broth containing 4 per cent Witte peptone, boiling, filtering and autoclaving. After inoculation with a suitable strain of staphylococcus, the poison can be demonstrated in the sterile Berkefeld filtrates of this broth after 24 hours growth, but our most toxic poisons were obtained after four to six days growth. The toxicity of the filtrates was tested by intracutaneous inoculation in rabbits. One-tenth cc. of filtrates was inoculated intradermally and at the same time a control of 0.1 cc. of uninoculated broth was always injected in the same rabbit. The reaction produced by the injection of a toxic filtrate becomes evident from two to six hours after injection as a bluishpurple area of 2 to 5 cm. in diameter, depending on the toxicity of the filtrate. The next day, the purple coltor assumes a yellow tinge, and there is usually added a deep red zone of 0.5 to 3 cm. surrounding the yellowish area. The circumsoribed yellowish area of 3 to 5 cm. becomes progressively yellower-as if necrotic. By the fifth day brown patches appear in the yellow area and increase in size until, at about the twentieth day, the whole lesion has become a dark brown scab. Four to eight weeks later the scab falls off leaving an ulcer. Microscopically the lesions show marked infiltration of polymorphonuclear leucocytes with necrosis of epidermis and underlying corium,

Observations of fluctuations of virulence of B. influenzæ

Conclusion 1. The virulence of B. influenza is very variable and this may have some bearing on the epidemiology of the disease influenza in man. 2. A few observations are present that may throw some light on the results of bacteriological studies of this disease.