Humoral and cell-mediated immune responses to leptospires in different human cases

Humoral and cell-mediated immune responses (CMI) to leptospirosis were studied in different groups of human patients. These included clinically suspected cases of leptospirosis, patients with jaundice (HBsAg negative), cases of pyrexia of unknown origin (PUC) (Widal and blood culture negative for typhoid) and healthy blood donors. Humoral immune response was evaluated with nine live strains representing different serogroups of leptospires and CMI with lysates of four strains. The study showed that the CMI appeared earlier than the humoral response which might be useful in the early detection of the disease. As in the humoral immune response, cross reactions to different leptospires were also seen in CMI response.