Deletion of SHIP-1 in Mice Leads to Diminished Th2 Responses to TCR Stimulation in vitro and Allergen Immunization in vivo

Abstract

RATIONALE: Src Homology 2 domain-containing inositol 5'-phosphatase 1 (SHIP-1) functions as a negative regulator of signaling pathways triggered by antigen, cytokine and Fc receptors in both lymphocytes and myeloid cells. We have shown that SHIP-1 deficiency leads to a spontaneous allergic inflammation in the murine lung. However, the role of SHIP-1 in adaptive immune response is unclear. To determine the contribution of SHIP-1 in T-cell response, we examined in vitro stimulation of T cell receptor and in vivo ovalbumin (OVA)-induced lung inflammation in mice deficient in SHIP-1.METHODS: Splenocytes from SHIP-1−/− and wild type (WT) Balb/c mice were stimulated with immobilized anti-CD3 and anti-CD28 for 2 days and the levels of IL-4, IL-13, and IFN-γ were measured. SHIP-1−/− and WT mice were immunized with OVA in Alum. After intranasal OVA challenge, we analyzed lung histology, bronchoalveolar lavage (BAL) cell recovery/differential, cytokine and chemokine expression, and airway hyperresponsiveness. We also determined cytokine production by cells from peritrachea lymph nodes and spleen after antigen re-stimulation.RESULTS: Compared with WT mice, OVA challenged SHIP-1−/− mice (OVA-SHIP-1) showed decreased eosinophilic infiltration into the lung, lower level of OVA-specific IgE in the serum, and diminished levels of IL-4 and IL-13 in the BAL. Lymphocytes from OVA-SHIP-1 released decreased amount of IL-4 and IL-13 in response to OVA stimulation.CONCLUSIONS: These results demonstrate that SHIP-1 deficiency leads to diminished Th2 responses in vitro and in vivo, suggesting that, in contrast to innate immunity, SHIP-1 may play a critical role in Th2 responses in adaptive immunity. RATIONALE: Src Homology 2 domain-containing inositol 5'-phosphatase 1 (SHIP-1) functions as a negative regulator of signaling pathways triggered by antigen, cytokine and Fc receptors in both lymphocytes and myeloid cells. We have shown that SHIP-1 deficiency leads to a spontaneous allergic inflammation in the murine lung. However, the role of SHIP-1 in adaptive immune response is unclear. To determine the contribution of SHIP-1 in T-cell response, we examined in vitro stimulation of T cell receptor and in vivo ovalbumin (OVA)-induced lung inflammation in mice deficient in SHIP-1. METHODS: Splenocytes from SHIP-1−/− and wild type (WT) Balb/c mice were stimulated with immobilized anti-CD3 and anti-CD28 for 2 days and the levels of IL-4, IL-13, and IFN-γ were measured. SHIP-1−/− and WT mice were immunized with OVA in Alum. After intranasal OVA challenge, we analyzed lung histology, bronchoalveolar lavage (BAL) cell recovery/differential, cytokine and chemokine expression, and airway hyperresponsiveness. We also determined cytokine production by cells from peritrachea lymph nodes and spleen after antigen re-stimulation. RESULTS: Compared with WT mice, OVA challenged SHIP-1−/− mice (OVA-SHIP-1) showed decreased eosinophilic infiltration into the lung, lower level of OVA-specific IgE in the serum, and diminished levels of IL-4 and IL-13 in the BAL. Lymphocytes from OVA-SHIP-1 released decreased amount of IL-4 and IL-13 in response to OVA stimulation. CONCLUSIONS: These results demonstrate that SHIP-1 deficiency leads to diminished Th2 responses in vitro and in vivo, suggesting that, in contrast to innate immunity, SHIP-1 may play a critical role in Th2 responses in adaptive immunity.