Beryllium skin patch testing to analyze T cell stimulation and granulomatous inflammation in the lung

Chronic beryllium disease (CBD) is characterized by granulomatous inflammation and the accumulation of CD4(+) T cells in the lung. Patch testing of CBD patients with beryllium sulfate results in granulomatous inflammation in the skin. We investigated whether the T cell clonal populations present in the lung of CBD patients would also be present in the involved skin of a positive beryllium patch test and thus mirror the granulomatous process in the lung. CBD patients with clonal TCR expansions in bronchoalveolar lavage (BAL) were selected for study. All three CBD patients studied had a positive response to beryllium sulfate application and a negative patch test to normal saline. Immunohistochemistry showed extensive infiltration with CD4(+) T cells and few, if any, CD8(+) T cells both at 3 days and at later times when granulomas were apparent. T cell infiltration early after skin testing appeared to be nonspecific with the TCR repertoire of infiltrating T cells being distinct from that present in BAL. At later times when granulomas were present, T cell clones in skin overlapped with those in BAL in all patients tested. Total TCR matches in skin and BAL were as high as 40% in selected Vbeta T cell subsets. Studies of peripheral blood T cells before and after patch testing provided evidence for mobilization of large numbers of pathogenic beryllium-reactive T cells into the circulating pool. These studies using skin patch testing provide new insight into the dynamics of T cell influx and mobilization during granulomatous inflammation.