IMMUNOREGULATION OF MALARIAL INFECTION - BALANCING THE VICES AND VIRTUES

Malaria continues to extract an incalculable cost on human morbidity a nd mortality throughout tropical and subtropical regions of the world, and effective control measures are urgently needed. Despite considera ble efforts in recent years to develop subunit vaccines targeted at va rious stages of the Plasmodium life-cycle, the commercial availability of a vaccine is still a distant prospect. One of the underlying diffi culties hindering successful vaccine design is our incomplete knowledg e of the precise type(s) of immune response to aim for, and then how t o achieve it. A greater appreciation of the mechanisms of protective i mmunity, on the one hand, and of immunopathology, on the other, should provide critical clues on how manipulation of the immune system may b est be achieved. Ten years have passed since the identification of the Th1/Th2 paradigm for distinguishing CD4(+) T cells according to cytok ine secretion patterns which determine their function. This review sum marises our progress towards understanding the broad spectrum of immun e responsiveness to the blood stages of the malaria parasite during ex perimental infections in mice and highlights the way in which examinat ion of rodent malarias provides a powerful tool to dissect the interac tion of Th1 and Th2 cells during an immune response to an infectious d isease agent. It is proposed that the pliability of rodent systems for investigating immunoregulation provides valuable insight into the bal ance between protection and pathology in human malaria and throws ligh t on the factors involved in the modulation of vaccine-potentiated imm unity. (C) 1998 Australian Society for Parasitology. Published by Else vier Science Ltd.