The study analyzed gene expression in peripheral blood mononuclear cells (PBMCs). Dr. Mellins justifies the use of PBMCs as being reflective of the systemic nature of SJIA, suggesting that the blood is a reasonable window into the disease. This strategy was supported by the signal differences that were measured in the study. Dr. Mellins acknowledged, however, that “It would be great to be able to look directly at the cells in joints.” The fact that, typically, there is no clinical reason to get samples from the joints makes it difficult to justify such an approach. This limitation in the study design underscores the need for a good animal model for SJIA.
Dr. Pullen is a medical writer based in the Chicago area.
1. Ling XB, Macaubas C, Alexander HC, et al. Correlation analyses of clinical and molecular findings identify candidate biological pathways in systemic juvenile idiopathic arthritis. BMC Med. 2012;10:125.