Increased systemic T-lymphocyte reactivity in patients with established stroke.

We have analyzed the impact of stroke with subsequent hemiparesis and sensory loss on systemic in vivo and in vitro mediated immune functions. Delayed-type hypersensitivity (DTH) reaction to purified protein derivate (PPD, tuberculin), evaluated on the non-paretic side, was used as an in vivo measure of systemic antigen specific T-cell reactivity. Subcutaneous immunization with influenza vaccine was employed to analyse T-cell dependent B-cell function. The influence of stroke on T-cell function in vitro was studied by proliferative responses to PPD and Concanavalin A. Twenty five out of 54 (46%) stroke patients tested displayed positive DTH reaction to PPD. In contrast, only 24% of age matched controls displayed positive DTH reaction (p < 0.05). There was a good correlation between in vivo and in vitro reactivity to PPD. Consequently, peripheral blood mononuclear cells in 50% of stroke patients but only in 20% of matched controls showed proliferative response in vitro to PPD. Immunization of stroke patients and controls with influenza vaccine, a T-cell dependent B-cell antigen, raised equal antigen-specific serum IgG, IgA and IgM antibody responses in both study groups. We conclude that (a) stroke enhances systemic antigen-specific T-cell reactivity in vivo and in vitro, and (b) stroke has no significant effect on antigen-specific B-cell responses.