IPP and systemic sclerosis: Further functional studies revealed, in a study of 16 SSc patients and 16 HCs, that ex vivo triggering of patient PB Vγ9+ T cells with IPP plus IL-2-induced dose-dependent expansion, resulted in secretion of TNFα, and contact-dependent apoptosis of co-cultured fibroblasts, at levels similar to Vγ9+ T cells of controls [103].