Delayed Hypersensitivity to Trichinella spiralis Antigens in Irradiated Guinea Pigs

Abstract

The development of the delayed type of hypersensitivity to Trichinella spiralis antigen in the guinea pig was not inhibited by total body x-irradiation up to 200 R when administered 18 hr prior to sensitization with antigen plus adjuvant. An X-ray dose of 200 R, however, seemed to inhibit partially the appearance of antibody in some animals for 21 days following sensitization as determined by the PCA test and seemed to inhibit the appearance of precipitating antibodies altogether. A decrease in the percentage of lymphocytes in irradiated animals may be responsible for the inhibition of antibody formation and for the failure of passive transfer by splenic cells. Delayed hypersensitivity was produced in response to both the acid-soluble protein fraction and the saline extract of Trichinella spiralis, particularly when injected in combination with Freund's complete adjuvant (Kim, 1965, 1966). The hypersensitive state was manifested by: (1) a delayed skin reaction that appeared after 4 hr and reached its maximum between 18 and 28 hr, (2) the absence of circulating antibodies when challenged with a shocking dose of the homologous antigen at the peak of the skin reaction, (3) the failure to detect precipitating antibodies by microimmunoelectrophoresis and microOuchterlony tests, (4) a perivascular infiltration of predominantly mononuclear cells (lymphocytes, monocytes, transitional forms, and macrophages) at the skin test site 18 to 28 hr following the skin test, and (5) the ability to transfer the hypersensitive state from sensitized donors to normal recipients by means of splenic cells in the absence of antibodies. As stated recently by Taliaferro et al. (1964), reports on the effect of irradiation on delayed hypersensitivity have been scarce. Salvin and Smith (1959) found that the induction of delayed hypersensitivity to diphtheria toxoid in the guinea pig was not inhibited by Received for publication 9 February 1966. *This investigation was supported by Public Health Service Fellowship 1-F3-AI-21,046-01 and 2-F3-AI-21,046-02 from NIH, U. S. Public Health Service, and in part by NIH Grant AI00884, U. S. Public Health Service, and in part by the U. S. Atomic Energy Commission. t Present address: Division of Microbiology, Medical Department, Brookhaven National Laboratory, Upton, Long Island, New York. total body irradiation up to 300 R. Uhr and Scharff (1959, 1960) showed that the capacity to develop the delayed type of hypersensitivity in the guinea pig irradiated with 200 R 24 hr prior to sensitization may persist even when detectable circulating antibody is not produced. In view of the above findings, the present experiments were designed using X-ray as a tool to study the relationship between the production of delayed hypersensitivity and the appearance of antibodies to T. spiralis antigen. MATERIALS AND METHODS The procedures for most of the following methods have been reported previously (Kim, 1966).