Proposed model explaining the difference in reactivity to Aβ during <i>in vivo</i> and <i>in vitro</i> stimulation between the CD4⁺CD28⁺ lymphocytes of high (HR) and low responders (LR).

<p>Arrows connect the type of responder (high vs. low) with expected response to stimulation. Dotted arrows: environmental Ag stimulation and response; dashed arrows: Aβ-specific (antigenic) stimulation and response; solid arrows: Aβ - immunomodulatory response.