The inducible co-stimulatory molecule (ICOS) is a CD28 homologue implicated in regulating T-cell differentiation. Because co-stimulatory signals are critical for regulating T-cell activation, an understanding of co-stimulatory signals may enable the design of rational therapies for immune-mediated diseases. According to the two-signal model for T-cell activation, T cells require an antigen-specific signal and a second, co-stimulatory, signal for optimal T-cell activation. The co-stimulatory signal promotes T-cell proliferation, lymphokine secretion and effector function. The B7-CD28 pathway provides essential signals for T-cell activation, but does not account for all co-stimulation. We have generated mice lacking ICOS (ICOS-/- ) to determine the essential functions of ICOS. Here we report that ICOS-/- mice exhibit profound deficits in immunoglobulin isotype class switching, accompanied by impaired germinal centre formation. Class switching was restored in ICOS-/- mice by CD40 stimulation, showing that ICOS promotes T-cell/B-cell collaboration through the CD40/CD40L pathway.

Neurological disorders pose a substantial health and economic burden to the individual and society, necessitating strategies for effective prevention and disease management. Lifestyle behaviours play a role in risk and management of some neurological disorders; however, overlap between lifestyle behaviours across disorders has not been well explored. We used log-binomial regression to assess associations of selected lifestyle behaviours in community-dwelling Australians (n = 192,091), some of whom self-reported Alzheimer’s disease (AD), motor neurone disease (MND), multiple sclerosis (MS), Parkinson’s disease (PD) or stroke. Of six lifestyle behaviours, undertaking physical activity was inversely associated with the presence of all neurological disorders except PD. Smoking was positively associated with MND and stroke, and inversely associated with PD. Participants with AD and stroke shared inverse associations with cognitive engagement, face-to-face social interaction and stress-reducing activities, and MS was positively associated with online social interaction and stress-reduction activities. Of eleven food and beverage consumption categories, no associations were seen in MND, ten categories were inversely associated with people with AD or stroke, and six of these with PD. Vegetable and soft drink consumption were associated with MS. Further detailed assessment of commonalities in lifestyle behaviours across neurological disorders may inform potential strategies for risk reduction across disorders.

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