James T. Culbertson

A study upon passive immunity in experimental trichiniasis.

Protection against infection with Trichinella spiralis is conferred upon mice by the passive transfer to them of a specific immune serum from rabbits. A smaller percentage of mice treated with the immune serum die, and fewer larvae invade the muscles of the treated mice than among control animals. The action of the antibody of the immune serum appears to be directed specifically against the ingested larvae which are maturing to adult worms in the intestine of the infected animals. The results obtained thus far indicate that an immune serum would have little therapeutic value in the later stages of the disease.

Antibody Production by the Rabbit Against an Ectoparasite

The itch mite, Psoroptes communis var. cuniculi, is a common ectoparasite upon the rabbit, large numbers being found upon the skin surface deep within the fold of the outer ear. The skin where the mites occur becomes necrotic and is sloughed off. If a small piece of the slough be examined with a low-power microscope, many mites can be seen crawling over it. It has occurred to the writer that repeated skin puncture by such numbers of ectoparasites, each injecting in the form of its saliva a small quantity of protein peculiar to the parasite, should lead to the production of specific antibody against the attacking species. We have endeavored to determine if this be true by testing for the presence of precipitin in 10 adult rabbits, 5 known to be infested with the parasites, these being observed in each case under the microscope, and 5 others apparently free of such infestation, neither the parasites nor their characteristic effects being detected upon careful search. The antigen—an extract of the mite—was prepared in the following manner. Pieces of the sloughed skin were removed with forceps from the infested ears and placed in a Petri dish. As we observed them with a low-power dissecting binocular, the mites could be seen to leave the skin and crawl about over the glass plate. They were picked up, best in groups of several, on the point of a dissecting needle and transferred to a small mortar. After about 300 mites were thus transferred, they were mashed with a pestle and triturated for 10 minutes with 1 1/2 cc. of Cocas solution. The mixture was then centrifugated at high speed and the very slightly opalescent supernatant fluid decanted.

Diagnosis of Echinococcal (Hydatid) Disease in Man by Intradermal Reaction to Rabbit Cysticercus Antigen

Summary An extract of cysticerci of the common rabbit cestode, Tænia pisiformis, has been used as an antigen for skin testing in cases of echinococcal infection. An antigenic relationship between Tænia pisiformis and Tænia echinococcus is suggested by the precipitin-reaction, the alexin fixation, and the skin reaction in rabbits harboring Tænia pisiformis. Four patients known to have hydatid disease gave immediate positive skin reactions with the rabbit antigen. Twenty normal subjects used as controls exhibited at most but slight reactions, and were considered negative.

FURTHER OBSERVATIONS ON SKIN REACTIONS TO ANTIGENS FROM HETEROLOGOUS CESTODES IN ECHINOCOCCUS DISEASE

Although the skin test is the most valuable single procedure for the diagnosis of echinococcus disease, its use for either the identification or the exclusion of possible infection is limited because the specific hydatid antigen is not easily obtained in many parts of the world in which suspected cases appear. In recent years, antigens derived from heterologous cestodes have been tried as substitutes for the specific hydatid substance in the immediate type of skin test and, in a number of instances, they have been found to serve the purpose about as well as those from the specific source (1). Several such skin-testing substances have been described previously by the authors (2) who have reported their diagnostic use in a small series of surgically proved, cases of echinococcus disease. In the present communication, further observations on skin tests in echinococcus disease are recorded which indicate that many different species of cestodes are a potential source of antigen suitable for eliciting an immediate reaction. Some of these tests were performed directly upon patients known to have the disease, while others were carried out on normal persons by the passive transfer method of Prausnitz and Kiistner (3).

Infection with Trypanosoma lewisi in the Hypophysectomized Rat

Trypanosoma lewisi is a natural parasite of the blood of wild rats, and can be transferred easily to laboratory rats. After inoculation to normal adult rats, it produces a blood stream infection of considerable intensity, although only rarely does the infected animal die. At the end of a patent period ranging from a few day to several weeks, the animals usually clear themselves of the infection and thereafter wholly resist reinfection with this parasite. 1 In the present paper are reported the results of infecting hypophysectomized rats with Trypanosoma lewisi. As will be seen, the hypophysectomized rat dies after infection with this parasite, death occurring in most cases 5 days after the parasite is injected. Procedure. The experimental work was designed: (1) to compare infection with Tryp. lewisi in hypophysectomized rats with that in control rats,∗ and (2) to study the effect of the administration of anterior pituitary extract upon the infection in the hypophysectomized rats. Thirty-three rats 60 days old were used for the first purpose of the work, 19 being hypophyseetomized† and 14 serving as controls. At infection, all animals were given one million Tryp. lewisi intraperitoneally. The hypophysectomized rats, together with 12 of the control rats which were subjected to the identical operative procedure except for the removal of the hypophysis, were infected from 5 to 10 days after operation. The 2 remaining control rats were normal unoperated animals. For the second purpose of the work, 14 hypophysectomized rats, infected 5 days after operation, were treated subcutaneously or intraperitoneally daily with 10 rat units of E. R. Squibb and Sons′ anterior pituitary extract ‡ beginning the first day after operation and continuing until death or recovery from the infection.

Quantitative Method for Determination of Precipitin in Small Volumes of Rabbit Anti-Crystalline-Egg-Albumin-Serum

The usual dilution methods for determining the precipitin titer of antiserum only roughly approximate the relative antibody strength of a given serum and give no information with regard to the absolute quantity of antibody. Analysis of precipitates from the precipitinogen-precipitin reaction for their nitrogen content by the micro-Kjeldahl method has been used by Wu and his collaborators 1 and Heidelberger and Kendall. 2 Precise measurements of the antibody per unit volume of antiserum, and exact studies on the ratio of antigen to antibody in the precipitate have thus been made possible. This method requires at least 0.5 cc. of serum for each test and cannot be used when only small volumes of antiserum are available. We have found that the following procedure gives satisfactory results for determining the quantity of precipitin in a small volume of rabbit anti-crystalline-egg-albumin serum. The method was suggested by figures presented by Heidelberger and Kendall. It depends on the determination of the amount of antigen necessary to precipitate the precipitins completely from a given volume of an antiserum. This determination of the mg. of antigen necessary completely to precipitate the antibodies from a sample of such serum is easily accomplished without analytical methods because the point of maximum precipitation proves to be that point where antigen as well as antibody is completely precipitated and neither antigen nor antibody remains in the supernatant fluid. We have called this optimum ratio of antigen to antibody the neutralization point. Furthermore, at this optimum point antigen and antibody combine in a ratio of about 1;13. The description of the method will clarify these points. Method. The stock solution of crystalline egg albumin was diluted with saline to provide known concentrations of the antigen expressed in mg. of nitrogen per cc.

Blood Plasma Volume Determination by Injection of Anti-Crystalline-Egg-Albumin-Serum

The blood plasma volume of an animal is usually found by determining the dilution in the plasma of a known amount of an injected test substance following its introduction into the blood stream. Dyes and other chemical substances are generally employed. The dilution of the material in the plasma is found (1) colorime-trically, 1 , 2 (2) spectroscopically, 3 or (3) by chemical means. 4 There is a considerable variation in the figures obtained for blood plasma volume by these methods. This variation may be due partly to loss of the injected foreign material from the blood stream and partly to the difficulty of determining the dilution of the substance introduced. The injection of an immunologically distinct blood or serum would, presumably, be more harmonious with the blood and tissues of an experimental animal than a foreign dye or other chemical substance. The dilution of such a blood could be determined by means of immunological tests. This has been resorted to by several investigators for the determination of blood volume. The first to present this method was von Behring. 5 His procedure consisted in finding the dilution of a known amount of an antitoxic serum after its introduction into the blood stream. Later, Todd and White 6 employed isohemolysins to determine the dilution of blood from another animal of the same species after its injection. Ashby 7 described a similar method which made use of isohemagglu-tinins for finding the blood volume of man. These immunological methods have not been widely used, although they would seem potentially advantageous since a native animal protein is administered. This is in part perhaps because the immune reactions concerned seem to lack sufficient accuracy for determining the dilution of the injected blood.