Chronic beryllium disease (CBD) is caused by exposure to beryllium in the workplace, and it remains an important public health concern. Evidence suggests that CD4 + T cells play a critical role in the development of this disease. Using intracellular cytokine staining, we found that the frequency of beryllium-specific CD4 + T cells in the lungs (bronchoalveolar lavage) of 12 CBD patients ranged from 1.4% to 29% (mean 17.8%), and these T cells expressed a Th1-type phenotype in response to beryllium sulfate (BeSO 4 ). Few, if any, beryllium-specific CD8 + T cells were identified. In contrast, the frequency of beryllium-responsive CD4 + T cells in the blood of these subjects ranged from undetectable to 1 in 500. No correlation was observed between the frequency of beryllium-responsive bronchoalveolar lavage (BAL) CD4 + T cells as detected by intracellular staining and lymphocyte proliferation in culture after BeSO 4 exposure. Staining for surface marker expression showed that nearly all BAL T cells exhibit an effector memory cell phenotype. These results demonstrate a dramatically high frequency and compartmentalization of antigen-specific effector memory CD4 + cells in the lungs of CBD patients. These studies provide insight into the phenotypic and functional characteristics of antigen-specific T cells invading other inaccessible target organs in human disease.

No abstract

Chronic beryllium disease (CBD) is caused by exposure to beryllium in the workplace, and it remains an important public health concern. Evidence suggests that CD4(+) T cells play a critical role in the development of this disease. Using intracellular cytokine staining, we found that the frequency of beryllium-specific CD4(+) T cells in the lungs (bronchoalveolar lavage) of 12 CBD patients ranged from 1.4% to 29% (mean 17.8%), and these T cells expressed a Th1-type phenotype in response to beryllium sulfate (BeSO(4)). Few, if any, beryllium-specific CD8(+) T cells were identified. In contrast, the frequency of beryllium-responsive CD4(+) T cells in the blood of these subjects ranged from undetectable to 1 in 500. No correlation was observed between the frequency of beryllium-responsive bronchoalveolar lavage (BAL) CD4(+) T cells as detected by intracellular staining and lymphocyte proliferation in culture after BeSO(4) exposure. Staining for surface marker expression showed that nearly all BAL T cells exhibit an effector memory cell phenotype. These results demonstrate a dramatically high frequency and compartmentalization of antigen-specific effector memory CD4(+) cells in the lungs of CBD patients. These studies provide insight into the phenotypic and functional characteristics of antigen-specific T cells invading other inaccessible target organs in human disease.

T cell receptor engagement with CD28 costimulation is generally required for naive T cell activation, whereas reactivation of memory cells is less dependent on CD28 costimulation. We studied this process in chronic beryllium disease, in which the frequency of antigen-specific CD4+ T cells in the lung is large and circulating antigen-specific cells are also detectable. In the lung, a large fraction of CD4+ T cells stopped expressing CD28 mRNA and protein, and this change in phenotype correlated with lung inflammation. In the presence of concentrations of CTLA-4Ig that inhibited the CD28-B7 interaction, beryllium-specific CD4+ T cells in lung were still able to proliferate and secrete IFN-γ in response to beryllium in culture. This functional independence of CD28 costimulation included lung CD28+ effector cells. Although lung CD4+CD28– cells retained the ability to secrete Th1-type cytokines in response to beryllium, they showed less proliferative capacity and were more susceptible to cell death compared with CD28+ T cells. In contrast to lung cells, inhibition of the CD28-B7 interaction markedly reduced responses of beryllium-specific T cells in blood. Taken together, these findings suggest transition within memory CD4+ T cells from CD28 dependence in central memory cells to functional independence and then loss of CD28 expression in effector cells

Chronic beryllium disease (CBD) is caused by exposure to beryllium in the workplace, and it remains an important public health concern. Evidence suggests that CD4 + T cells play a critical role in the development of this disease. Using intracellular cytokine staining, we found that the frequency of beryllium-specific CD4 + T cells in the lungs (bronchoalveolar lavage) of 12 CBD patients ranged from 1.4% to 29% (mean 17.8%), and these T cells expressed a Th1-type phenotype in response to beryllium sulfate (BeSO 4 ). Few, if any, beryllium-specific CD8 + T cells were identified. In contrast, the frequency of beryllium-responsive CD4 + T cells in the blood of these subjects ranged from undetectable to 1 in 500. No correlation was observed between the frequency of beryllium-responsive bronchoalveolar lavage (BAL) CD4 + T cells as detected by intracellular staining and lymphocyte proliferation in culture after BeSO 4 exposure. Staining for surface marker expression showed that nearly all BAL T cells exhibit an effector memory cell phenotype. These results demonstrate a dramatically high frequency and compartmentalization of antigen-specific effector memory CD4 + cells in the lungs of CBD patients. These studies provide insight into the phenotypic and functional characteristics of antigen-specific T cells invading other inaccessible target organs in human disease.