A decomposition product of a contaminant implicated in L-tryptophan eosinophilia myalgia syndrome affects spinal cord neuronal cell death and survival through stereospecific, maturation and partly interleukin-1-dependent mechanisms.

The L-tryptophan eosinophilia myalgia syndrome (L-TRP-EMS), an inflammatory syndrome characterized by eosinophilia, myalgias, perimyositis, fasciitis and neuropathies, occurred in epidemic proportions in the United States in the summer and fall of 1989. The neuropathic clinical features in L-TRP EMS are complex and mixed. In the present study, one of the impurities most highly associated with development of L-TRP EMS, 1,1'-ethylidenebis[L-tryptophan] (EBT), and two of its diastereoisomeric breakdown products, were compared for evidence of neurotoxicity in vitro. In 1-month-old spinal cord cultures derived from fetal mice, synthetic (-)-(1S,3S)-1-methyl-1,2,3,4-tetrahydro-beta-carboline-3-carboxylic acid (1S-beta-C) produced a 30 to 35% loss in numbers of neurons. Toxicity was not apparent after treatment with the R-isomer of the same compound or with the parent compound, EBT. Cotreatment of cultures with 1S-beta-C and neutralizing antiserum to interleukin-1 alpha (IL-1 alpha), or with 1S-beta-C and neutralizing antiserum against the murine IL-1 receptor, prevented neuronal cell death associated with 1S-beta-C. Recombinant IL-1 alpha also produced neuronal killing that was not additive to that observed with the 1S-beta-C treatment. In contrast, in immature spinal cord neuronal cultures, the 1S-beta-C, but not the 1R-beta-C or EBT, prevented the 30% cell death which normally occurs in these cultures. Neither neutralizing anti-IL-1 antibody, nor anti-IL-1 receptor antibody blocked the neuronal survival effect, suggesting that 1S-beta-C induces neuronal survival through a receptor-mediated mechanism independent of IL-1.(ABSTRACT TRUNCATED AT 250 WORDS)