Activation pathways implicate anti-HLA-DP and anti-LFA-1 antibodies as lead candidates for intervention in chronic berylliosis

CD4⁺ T cells play a key role in granulomatous inflammation in the lung of patients with chronic beryllium disease. The goal of this study was to characterize activation pathways of beryllium-responsive bronchoalveolar lavage (BAL) CD4⁺ T cells from chronic beryllium disease patients to identify possible therapeutic interventional strategies. Our results demonstrate that in the presence of APCs, beryllium induced strong proliferation responses of BAL CD4⁺ T cells, production of superoptimal concentrations of secreted proinflammatory cytokines, IFN-γ, TNF-α,and IL-2, and up-regulation of numerous T cell surface markers that would promote T-T Ag presentation. Ab blocking experiments revealed that anti-HLA-DP or anti-LFA-1 Ab strongly reduced proliferation responses and cytokine secretion by BAL CD4 ⁺ T cells. In contrast, anti-HLA-DR or anti-OX40 ligand Ab mainly affected beryllium-induced proliferation responses with little impact on cytokines other than IL-2, thus implying that nonproliferating BAL CD4 ⁺ T cells may still contribute to inflammation. Blockade with CTLA4-Ig had a minimal effect on proliferation and cytokine responses, confirming that activation was independent of B7/CD28 costimulation. These results indicate a prominent role for HLA-DP and LFA-1 in BAL CD4⁺ T cell activation and further suggest that specific Abs to these molecules could serve as a possible therapy for chronic beryllium disease.