Chemotactic response to SDF-1 of circulating T lymphocytes isolated from SS patients and healthy donors. (A) Chemotactic response of CD4⁺ SS cells and CD4⁺ control cells following exposure to increasing concentrations of SDF-1 (5 to 500 ng/mL) with a typical bell-shaped response curve. Results (mean ± SEM from 3 separate experiments) are shown as migration indexes representing the ratio between the number of cells that migrated in the presence of SDF-1 and the number of cells that migrated in response to medium alone. ^*Significant differences between controls (▪) and SS (□) by the Student t test (controls, n = 4; SS, n = 7; P < .05). (B) Cells that migrated in the lower chambers in response to SDF-1 were collected and stained with hematoxylin-eosin to evaluate their morphologic features. Original magnification × 40.