INFLUENCE OF CYCLOPHOSPHAMIDE ON DELAYED-HYPERSENSITIVITY AND ACQUIRED CELLULAR RESISTANCE TO LISTERIA-MONOCYTOGENES IN MOUSE

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  • 1 January 1977
    • journal article
    • research article
    • Vol. 32  (6) , 1027-1032
Abstract
The effect of a single dose of cyclophosphamide (CY) on delayed type hypersensitivity (DH) and acquired cellular resistance (ACR) to L. monocytogenes infection in mice was studied. I.p. or intracutaneous immunization with L forms of L. monocytogenes did not result in protection against lethal challenge. A positive DH could be observed when CY-treated mice were intracutaneously immunized with 108 or more L forms. Injection i.p. of viable L. monocytogenes resulted only in a narrow dose range in survival on immunization and partial protection on challenge. Protection was accompanied by DH. Intracutaneous injection of Listeria in Freund''s complete adjuvant permitted the use of even 109 viable bacteria for immunization. This figure was reduced to 105 or less for CY treated mice. In normal mice protection was afforded on immunization with 107 bacteria, whereas 103 bacteria were sufficient to protect CY treated animals. All protected mice showed a positive DH. CY treatment reduces the dose of viable bacteria tolerated for immunization 104 times. After CY treatment the doses of bacteria effective on immunization for ACR and DH could be reduced in the same order of magnitude. Reduction of the CY dose resulted in a peak DH with 4 mg CY, but the protection was less than that obtained after treatment with 6 mg CY. A dissociation between ACR and DH was observed by varying the interval between immunization and challenge. In normal mice DH was preceded by ACR, with peaks at respectively 10 and 5 days after immunization. CY treatment caused a delay in the onset of the ACR, followed by an enhanced and slightly prolonged response. The effect of CY and DH consisted of enhancement and prolongation.