['Signaling through CD28 family co-receptors regulates activation of CD4(+) T cells positively and negatively. It has been shown that stimulatory co-receptors such as CD28 and ICOS play critical roles in the induction of allergic airway inflammation. However, the role of B and T lymphocyte attenuator (BTLA), an inhibitory co-receptor expressed preferentially in Th1 cells, in the regulation of allergic airway inflammation remains to be determined.', 'We examined antigen-induced eosinophil recruitment and cytokine production in the airways in antigen-sensitized BTLA-deficient (BTLA-/-) mice. We also examined antigen-induced cytokine production and cell proliferation of splenic T cells in antigen-sensitized BTLA-/- mice.', 'Antigen-induced eosinophil recruitment and IL-5 production in the airways was enhanced in antigen-sensitized BTLA-/- mice. On the other hand, antigen-induced Th1 and Th2 cytokine production as well as T cell proliferation of splenocytes was normal in BTLA-/-mice.'] Does b and T lymphocyte attenuator inhibit antigen-induced eosinophil recruitment into the airways?