The Functional Role of B Cells in a Mouse Model of Autoimmune Lacrimal Keratoconjunctivitis: Adoptive Transfer of Serum, but Not B Cells Alone, Mediates Ocular Surface Inflammation

Abstract

Purpose: : To evaluate the functional role of B cells in the immunopathogenesis of experimental autoimmune lacrimal keratoconjunctivitis (ALKC).

Methods: : Experiments were designed to determine if B cells are pathogenic in the context of ALKC by evaluating their i) role as antigen presenting cells (APC), ii) potential to mediate or augment ALKC and iii) putative role as autoantibody secreting cells. Experimental ALKC was induced by exposing female C57BL/6 wild-type (WT) mice to desiccating stress [DS: subcutaneous scopolamine (0.5 mg/0.2ml) TID, humidity <40%, and sustained airflow] for up to 3 weeks. To evaluate the role of B cells as APCs, control (CT) or 10 day DS-specific B cells and CT or DS CD4+ T cells purified from the cervical lymph nodes and spleen were co-cultured for 4 days; the CD4+ T cell proliferative response was measured by WST assay. Further, to determine if B cells or serum contribute to ALKC, DS-specific B cells (10 days DS) or DS serum (3 weeks DS) was adoptively transferred into nude recipient mice, which were subsequently evaluated for ocular surface inflammation 3 days post-transfer.

Results: : CD4+ T cells purified from ALKC mice and co-cultured with DS-specific B cells (98% pure) displayed ~20% (p=0.003) more proliferation by WST than CD4+ T cell isolated from naïve mice. However, DS B cells did not mediate or augment ocular surface inflammation in nude recipient mice when adoptively transferred alone or when co-transferred with DS-specific CD4+ T cells. By contrast, nude recipient mice that received DS serum displayed a dose-dependent increase in tear cytokine levels of IL-1α (p=0.03), IL-1β (p=0.03) and TNF-α (p=0.04) compared to control mice.

Conclusions: : These results indicate that DS-specific serum, but not B-cells alone, induces ocular surface inflammation in the context of the nude recipient mouse. Collectively, the data suggests that ALKC-specific autoantibodies may contribute to T cell-mediated immunopathogenesis of experimental ALKC.

Keywords: cytokines/chemokines • inflammation • conjunctiva