Abstract

MC Moreno-Lafont, A Lopez-Merino and R Lopez-Santiago Departamento de Inmunologia, Escuela Nacional de Ciencias Biologicas, Colonia Santo Tomas, Mexico D.F., Mexico. We compared the immunological responses of leukocytes taken from healthy negative controls, laboratory workers immunized with the phenol- insoluble French vaccine against brucellosis, patients acutely ill with brucellosis, and patients chronically infected with Brucella melitensis. A salt-extractable antigen (protein-rich but with traces of lipopolysaccharide) and a sonicated suspension from B. melitensis 16M were used as antigens for in vitro lymphocyte proliferation test. Quantitation of T cells showed that the ratio of CD4+/CD8+ cells decreased as the condition of the patient deteriorated. An assay to quantitate the cell-mediated immunity showed that the activities of mononuclear cells stimulated with concanavalin A increased as the disease progressed as well.