The expanding role of microarrays in the investigation of macrophage responses to pathogens.

In the last few years, microarray technology has emerged as the method of choice for large-scale gene expression studies. It provides an efficient and rapid method to investigate the entire transcriptome of a cell. No research field has benefited more from microarray technology than the study of the exquisite interplay between pathogens and hosts. Numerous microarray studies have now been published in this field, which have provided insights into the mechanisms of host defence and the tactics employed by pathogens to circumvent these protection strategies. These studies have led to a more comprehensive understanding of the host immune response and identified new avenues of research for potential control strategies against pathogens. In the past, research has concentrated on human and mouse microarrays to investigate host-pathogen interactions, regardless of the host species. This trend is changing with the ever-expanding sequence resources now available for many pathogen and host species, including livestock animals. The use of species-specific microarrays has furthered our understanding of host-pathogen interactions for particular organisms and aided in the annotation of unknown genes. Macrophages play a central role in the host's innate and adaptive immune responses to pathogens. These cells are in the first line of defence and interact with a wide range of pathogens; many of which have evolved strategies to circumvent the macrophage defence mechanisms and survive within these cells. In this report, we review the wealth of studies using microarray technology to investigate the response of macrophages to pathogens. These studies illustrate how microarray technology has expanded our understanding of the dialogue between macrophage and pathogen and provide examples of the benefits and pitfalls of using this technique. Furthermore, we discuss the resources available to use microarray analysis to study the immune response of a non-human, non-rodent species, the cow.