SILICONE-SPECIFIC BLOOD LYMPHOCYTE-RESPONSE IN WOMEN WITH SILICONE BREAST IMPLANTS

A blinded cross-sectional study was carried out with 99 women, 44 of w hom had silicone breast implants. Group I consisted of 55 healthy volu nteer women without breast implants; group II comprised 13 volunteer w omen with breast implants or explants who felt healthy; group III comp rised 21 volunteer women with breast implants who had chronic fatigue, musculoskeletal symptoms, and skin disorders; and group IV comprised 10 women who had their prostheses explanted but still presented with c linical symptoms similar to those of the women in group III. Prolifera tive responses of peripheral blood mononuclear cells from all 99 women were measured by [H-3]thymidine uptake after exposure to SiO2, silico n, or silicone gel. The levels of proliferative responses were express ed as stimulation indices, which were obtained by dividing the counts per minute of stimulated cells by the counts per minute of unstimulate d cells. Abnormal responses to SiO2, silicon, or silicone gel were def ined as a stimulation index of >2.8, > 2.1, or > 2.4, respectively. Ab normal responses were observed in 0% of group I, 15% of group II, 29% of group III, and 30% of group IV (P < 0.0005 for group I versus group s II and IV). Thirty-one percent of symptomatic women with silicone ge l breast implants had elevated serum silicon levels (> 0.18 mg/liter); however, there was no significant correlation between abnormal cellul ar responses and silicon levels in blood serum, type of implant, time since first implantation, prothesis explantation, number of implants, or report of implant leakage or rupture. Flow cytometric and cell depl etion analyses showed that the responding cells were CD4+ T cells, wit h no apparent contribution from the CD8+ T-cell population. Our demons tration that silicon-specific T-cell responses are observed in twice a s many symptomatic as asymptomatic women exposed to silicone breast im plants suggests that cell-mediated immunity plays a role in the develo pment of abnormal immune reactions associated with silicone and provid es a new, apparently specific screening blood test. Whether the activi ty observed in asymptomatic women is predictive of symptom development is under prospective study.