Novel multi-probe RNase protection assay (RPA) sets for the detection of murine chemokine gene expression

Chemokines play an essential role in immune and inflammatory reactions via the recruitment of leukocytes. Studying the role of chemokines in vivo is complicated by the redundancy of their action and by their promiscuous receptor usage. The simultaneous analysis of several chemokines is, therefore, advantageous in order to obtain a comprehensive view of chemokine participation in inflammatory and infectious processes. At present, no multi-probe detection systems are available for the analysis of recently described chemokines. In this study, new multi-probe RNase protection assay (RPA) template sets were developed for the analysis of murine chemokines. Chemokine cDNA fragments were generated by RT-PCR and individually subcloned into the plasmid pGEM-T providing a T7 promotor. In this way, two multi-probe template sets were constructed each containing six chemokine sequences (CXCL12/SDF-1, XCL1/lymphotactin, CCL20/exodus-1, CCL25/TECK, CX3CL1/fractalkine, CXCL1/KC, and CCL20/MDC, CXCL9/MIG, CCL9/10/MIP-1γ, CXCL13/BLC, CCL12/MCP-5, CCL19/ELC, respectively) and templates for the two house-keeping genes L32 and GAPDH. The evaluation of these RPA template sets in various murine models demonstrated their suitability for the analysis of the above chemokines both under constitutive and infection-induced conditions. To reduce the personal radiation hazard, we found that ³²P could be replaced by ³³P without any loss of assay-sensitivity. These new RPA multi-probe sets provide valuable tools for the simultaneous quantitative determination of gene expression of multiple murine chemokines of both constitutive and inducible type.