In three patients with leptospirosis, improvement of clinical symptoms was closely associated with the appearance of agglutinating, complement-fixing, and hemolytic antibodies in the circulation. Elevations in the serum concentrations of IgG, IgA, and IgM were also demonstrated. In one patient, recurrence of fever and meningitis during the immune phase coincided with the appearance of agglutinins and increases in the levels of all three immunoglobulins in the spinal fluid. Ultracentrifugation of immune sera in sucrosedensity gradients showed that IgM was the predominant immunoglobulin involved in the agglutination, complement-fixation, and hemolytic tests. Although antibodies are important in the development of immunity during the septicemic phase, its role in the pathogenesis of clinical symptoms during the immune phase is still unclear.
Los Angeles County-USC Medical Center, Los Angeles, California 90033.
Immunology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20014.
Department of Medicine, Wadsworth Veterans Administration Hospital, Los Angeles, California 90073.
U. S. Naval Medical Research Unit No. 2, Taipei, Taiwan.