Following traumatic injury to the spinal cord, hematogenous inflammatory cells including neutrophils, monocytes, and lymphocytes infiltrate the lesion in a distinct temporal sequence. To examine potential mechanisms for their recruitment, we measured chemokine mRNAs in the contused rat spinal cord, using specific and sensitive reverse transcriptase polymerase chain reaction (RT-PCR) dot-blot hybridization assays. The neutrophil chemoattractant GRO-alpha was 30-fold higher than control values at 6 hr postinjury and decayed rapidly thereafter. LIX, a highly related alpha-chemokine, also was elevated early postinjury. Monocyte chemoattractant peptide (MCP)-1 and MCP-5 mRNAs, potent chemoattractants for monocytes, were significantly elevated at the lesion epicenter at 12 and 24 hr postinjury and declined thereafter. Interferon-gamma-inducible protein, 10 kDa (IP-10), chemoattractant towards activated T-lymphocytes, was significantly elevated at 6 and 12 hr postinjury. The dendritic cell chemoattractant MIP-3alpha also was increased, perhaps contributing to the development of T-cell autoreactivity to neural components after spinal cord injury (SCI) in rats. Other beta-chemokines, including MIP-1alpha and RANTES (regulated on expression normal T-cell expressed and secreted), were minimally affected by SCI. Expression of chemokines, therefore, directly precedes the influx of target neutrophils, monocytes, and T-cells into the spinal cord postinjury, as noted previously. Thus, selective chemokine expression may be integral to inflammatory processes within the injured spinal cord as a mechanism of recruitment for circulating leukocytes.