Immunosuppression in Rodent Malaria

Effect upon Recovery and Antibody Response

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  • U.S. Department of Health, Education, and Welfare, National Institutes of Health, National Institute of Allergy and Infectious Diseases, Laboratory of Parasitic Diseases, Bethesda, Maryland 20014

Three forms of immunosuppression (splenectomy, antilymphocyte serum [ALS], and hydrocortisone) were studied in mice infected intraperitoneally with Plasmodium berghei yoelii (2 × 106 parasitized erythrocytes). Splenectomy, performed 10 days before infection, impaired antibody synthesis and converted this self-limited infection to a 100% lethal infection. Antibody was measured by the indirect fluorescent-antibody (IFA) test. ALS (0.3 ml intraperitoneally every 3 days starting 6 days before infection and continuing through the infection) and hydrocortisone (4 mg intraperitoneally daily starting 1 day before infection and continuing through the infection) also impaired both antibody synthesis and recovery, but most mice eventually overcame the infection. In survivors, the appearance of antibody coincided with a decrease in parasitemia, suggesting that a humoral immunity is one of the factors essential to recovery from this malaria.