Seasonal changes in suppressive capacity of CD4+ CD25+ T cells from patients with hayfever are allergen-specific and may result in part from expansion of effector T cells among the CD25+ population.

BACKGROUND: Suppression of allergen-stimulated peripheral blood CD4(+) CD25(-) effector T cells by CD4(+) CD25(+) regulatory T cells obtained from subjects with allergic rhinoconjunctivitis is reduced during the pollen season when compared with out of season. OBJECTIVE: We examined possible explanations for this effect of seasonal pollen exposure on suppression of allergen responses. METHODS: CD4(+) CD25(-) and CD4(+) CD25(+) T cells were isolated from blood obtained from 44 volunteers with allergic rhinoconjunctivitis during and out of the UK grass pollen season. Co-cultures were performed with grass pollen extract and house dust mite (HDM) to examine allergen specificity. The frequency of IL-5 and IL-10 producing cells was determined by ELISPOT and the expression of T cell activation markers and the CD25(+) regulatory T cell-associated transcription factor Foxp3 were examined. Lactic acid stripping of IgE was used to determine IgE dependence of T cell responses. RESULTS: The seasonal reduction in suppression by CD4(+) CD25(+) T cells was confirmed and was shown to be allergen specific because suppression of HDM-stimulated cultures was not affected significantly. The CD4(+) CD25(+) population contained IL-5 and IL-10 producing cells but increases in their frequencies with seasonal pollen exposure were not significant. Both activation marker and Foxp3 expression increased during the pollen season. IgE stripping reduced CD4(+) and CD4(+) CD25(-) T cell responses to allergen, but had no effect on suppression by CD4(+) CD25(+) T cells. CONCLUSION: The seasonal reduction in suppression of grass pollen-stimulated effector T cells by CD4(+) CD25(+) T cells is allergen specific and cannot be explained by increased IgE-facilitated allergen presentation. We suggest that changes in the proportion of effector to regulatory T cells among the CD25(+) population isolated may partially explain these findings, and that trafficking to the site of allergic disease may reduce allergen-specific regulatory T cell numbers in peripheral blood.

The value of multichannel MEG and EEG in the presurgical evaluation of 70 epilepsy patients.

OBJECTIVE: To evaluate the sensitivity of a simultaneous whole-head 306-channel magnetoencephalography (MEG)/70-electrode EEG recording to detect interictal epileptiform activity (IED) in a prospective, consecutive cohort of patients with medically refractory epilepsy that were considered candidates for epilepsy surgery. METHODS: Seventy patients were prospectively evaluated by simultaneously recorded MEG/EEG. All patients were surgical candidates or were considered for invasive EEG monitoring and had undergone an extensive presurgical evaluation at a tertiary epilepsy center. MEG and EEG raw traces were analysed individually by two independent reviewers. RESULTS: MEG data could not be evaluated due to excessive magnetic artefacts in three patients (4%). In the remaining 67 patients, the overall sensitivity to detect IED was 72% (48/67 patients) for MEG and 61% for EEG (41/67 patients) analysing the raw data. In 13% (9/67 patients), MEG-only IED were recorded, whereas in 3% (2/67 patients) EEG-only IED were recorded. The combined sensitivity was 75% (50/67 patients). CONCLUSION: Three hundred and six-channel MEG has a similarly high sensitivity to record IED as EEG and appears to be complementary. In one-third of the EEG-negative patients, MEG can be expected to record IED, especially in the case of lateral neocortical epilepsy and/or cortical dysplasia.