¹Immunology Division, The Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria, Australia

Correspondence: Dr PD Hodgkin, Immunology Division, The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria 3050, Australia. E-mail: Hodgkin@wehi.edu.au

Received 22 March 2007; Accepted 23 March 2007; Published online 24 April 2007.

Abstract

Regulating the strength and class of an immune response requires lymphocytes to act as complex signal integrating 'machines', taking information from multiple sources while making decisions that affect the final outcome. Describing and understanding the decision-making behaviour of lymphocytes within the context of the dynamic multifaceted immune system appears immensely complicated. In this article I contrast two alternative frameworks, the deterministic and the probabilistic as competing paths to achieve successful quantitative immune models. As the two alternatives are traditional scientific rivals, I use the probabilistic fields in physics to highlight the potential value of the probabilistic perspective in immunology.