Analysis of responses of peripheral blood lymphocytes from sarcoidosis patients to purified protein derivative

Purpose: Negative skin test reaction against purified protein derivative (P PD) is one of the important diagnostic criteria for sarcoidosis. The purpos e of this study was to investigate the relationship between negative skin t est reaction against PPD and the responses of peripheral blood lymphocytes (PBLs) against PPD in sarcoidosis patients. Methods: Sarcoidosis patients (n = 14) with ocular changes were selected fo r this study. As a control, blood was collected from volunteers without uve itis (n = 10). All subjects in both groups had a history of bacille de Calm ette-Guerin vaccination, and 8 of the 14 patients underwent the PPD skin te st. Peripheral blood lymphocytes were obtained from all patients and separa ted by gradient centrifugation. Peripheral blood lymphocytes were tested fo r their proliferative responses to PPD. To determine the frequency of PPD-s pecific precursor calls in blood, limiting dilution analysis was used. The frequency was calculated following the Poisson model. The culture supernata nts were harvested 3 days after incubation and assayed for interferon (IFN) -gamma production by ELISA. Results: Four of the 8 patients showed a negative skin test reaction agains t PPD, while all the healthy volunteers had a positive reaction. Compared t o PBLs from healthy volunteers, PBLs from sarcoidosis patients showed weake r responses to PPD. There was no clear difference between these two groups about frequency of precursor cells against PPD and production of IFN-gamma. Conclusions: Negative skin test for PPD in sarcoidosis patients does not se em to have any relationship to the low precursor frequency of PPD-specific cells in patient blood. Jpn J Ophthalmol 2000;44:165-170 (C) 2000 Japanese Ophthalmological Society.