TY - JOUR T1 - Macrophages induce an allergen-specific and long-term suppression in a mouse asthma model JF - European Respiratory Journal JO - Eur Respir J SP - 1040 LP - 1046 DO - 10.1183/09031936.05.00089304 VL - 26 IS - 6 AU - J. L. M. Vissers AU - B. C. A. M. van Esch AU - G. A. Hofman AU - A. J. M. van Oosterhout Y1 - 2005/12/01 UR - http://erj.ersjournals.com/content/26/6/1040.abstract N2 - Increasing evidence suggests that macrophages (Mφ) play a crucial downregulatory role in the initiation and progression of allergic asthma. Recently, the current authors demonstrated that ovalbumin (OVA)-loaded Mφ (OVA-Mφ) suppress subsequent OVA-induced airway manifestations of asthma and that this effect could be potentiated upon selective activation. In the present study, the authors further delineated the underlying pathway by which Mφ exert this immunosuppressive effect. To examine the migration of OVA-Mφ, cells were labelled with 5′chloromethylfluorescein diacetate (CMFDA) and were administered (i.v.) into OVA-sensitised BALB/c mice. After 20 h, the relevant organs were dissected and analysed using fluorescent microscopy. Allergen-specificity was investigated by treating OVA-sensitised mice with keyhole limpet haemocyanin (KLH)-Mφ activated with immunostimulatory sequence oligodeoxynucleotide (ISS-ODN). By lengthening the period between treatment and challenge to 4 weeks it was examined whether OVA-Mφ exerted an immunosuppressive memory response. Strikingly, CMFDA-labelled Mφ were not trapped in the lungs, but migrated to the spleen. ISS-ODN-stimulated KLH-Mφ failed to suppress OVA-induced airway manifestations of asthma. Moreover, treatment with ISS-ODN-stimulated OVA-Mφ was still effective after lengthening the period between treatment and challenge. These data demonstrate that allergen-loaded macrophages can induce an indirect immunosuppressive response that is allergen-specific and long lasting, which are both hallmarks of a memory lymphocyte response. ER -