Lack of Interleukin-5 Production by T-Lymphocytes Isolated from Fibromyalgia Patients and Normal Controls After Being Cultured with 1,1′-Ethylidenebis Tryptophan, a Suspected Causal Contaminant of Eosinophilia-Myalgia Syndrome

Abstract

Objective: We investigated whether peripheral T-lymphocytes from 17 fibromyalgia patients [FMS], compared with normal controls, would show increased production of interleukin-5 [IL-5] when cultured with tryptophan [TRP] or with 1,1′-ethylidenebis tryptophan [EBT, TRP-dimer], a contaminant of a single manufacturer's over-the-counter commercial tryptophan preparation suspected of contributing to the eosinophilia-myalgia syndrome [EMS].

Methods: T-lymphocytes were cultured for 72 hours with increasing concentrations of EBT and TRP. Supernatants from these cultures and from culture controls were analyzed for IL-5 by a commercial enzyme-linked immunosorbent assay.

Results: Neither FMS nor control group produced a consistent dose-dependent IL-5 response to stimulation by TRP or EBT except one FMS patient and one control. Control T-lymphocytes produced normal amounts of IL-5 in vitro when stimulated by a mitogen, while the response of FMS T-lymphocytes was less.

Conclusion: Overall, these data appear to indicate that peripheral T-lymphocytes from FMS patients and normal controls are not hyperreactive to EBT or TRP. As such, they argue against an etiologic role for EBT in causing eosinophilia seen in EMS; however, further research is warranted based on responses seen in two study participants.

KEYWORDS:

• Fibromyalgia
• eosinophilia-myalgia syndrome
• interleukin-5
• L-tryptophan
• 1,1′-ethylidenebis tryptophan