Exposure to Th2 challenge by infection of mice with helminth parasites Schistosoma mansoni, or Heligmosomoides polygyrus, resulted in an increase in cardiac macrophage density, adoption of a stellate morphology and increased expression of Ym1, RELMα and CD206 (mannose receptor), indicative of ‘M2’ polarisation. This evidence concerns the gene MRC1 and infection.