We investigated whether antibody production to antigens arising in the subarachnoid space is depressed acutely after spinal cord injury (SCI), and whether such depression is due to abnormal catecholamine levels. To assess antibody responses, ovalbumin (OVA) was injected into the spinal subarachnoid space (i.t.) of rats via an indwelling catheter after SCI at T4 or laminectomy (LAM). Antibody responses tested at days 0, 7, and 14 (d0, d7, d14) postinjury revealed that SCI animals exhibited an antibody response significantly lower than LAM animals on d7, but one that reached control levels by d14. ELISPOT assays indicated that the cervical lymph nodes, known to be innervated by superior cervical ganglia (SCG), processed i.t. OVA. The reduction in antibody production after SCI could not be mimicked with surgical deafferentation of the SCG. However, blockade of beta-adrenergic receptors prior to SCI did reverse the decrease, suggesting an adverse effect of the surge of catecholamines that accompanies the injury. Surgical removal of sympathetic inputs to the cervical lymph nodes prior to SCI failed to reverse the effect on antibody production, suggesting a systemic source of catecholamines. We conclude that antibody responses against i.t. antigens are attenuated acutely after SCI due to the massive release of systemic catecholamines that accompanies SCI.