Safety of Silicone Breast Implants (1999) / Chapter Skim
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6 Immunology of Silicone
6 Immunology of Silicone
Pages 179-197
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From page 179... ...
IMMUNE RESPONSE TO SILICONE IN EXPERIMENTAL ANIMALS Studying effects on the immune response in various experimental animals is an approach to investigating a substance that is often employed by basic and clinical scientists. Currently available experimental data indicate that silicone gel (or some higher molecular weight silicone 179
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From page 180... ...
in a different site did not augment the immune response (Bradley et al., 1994a,b; Klykken and White, 1996~. Other animal studies of components of the immune response from several groups have shown that parenteral administration of silicone gel to animals induces a time-dependent decrease in natural killer (NK)
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From page 181... ...
Such autoreactivity, if induced by breast implants, should be demonstrated by self T-cell reactivity or sensitization when T-cells are exposed to self-antigens or components of silicone gels. In exploring whether silicone breast implants cause an autoimmune disorder in breast implant recipients, the committee concludes that it is important to determine if there is an abnormal immune response in these women that is directly caused by the implant.
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From page 182... ...
In particular, cytokine production from breast tissues that had been exposed to components of silicone breast implants and from skin involved in previous surgeries was not significantly different. Moreover, no correlation was recorded between systemic symptoms and actual measured cytokine production by explanted capsular tissues.
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From page 183... ...
Differences were found between women with silicone breast implants and healthy age-matched controls, but no valid conclusions were possible because symptomatic women with silicone breast implants were not compared to well women with implants to determine if implantation itself is associated with an increase in either IL-1p or IL-1 receptor antagonist (Ojo-Amaize et al., 1994~. Other studies showed no differences between women with breast implants compared to ageand sex-matched surgical patient controls when TNFoc and IL-6 as well as soluble TNF receptor were examined (Zazgornik et al., 1996~.
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From page 184... ...
Consistent with animal toxicology studies noted earlier, it appears that NK cells in humans might be affected by exposure to silicone gel, since removal of silicone breast implants was followed by an increase in NK-cell function in 50% of women studied by Campbell et al.
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From page 185... ...
There is no evidence to indicate that fibromyalgia is an autoimmune disease. Current evidence suggests that HLA haplotypes of symptomatic women with silicone breast implants resemble those of symptomatic women without breast implants.
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From page 186... ...
in symptomatic women with silicone breast implants. The symptomatic patients appeared to show higher Tcell stimulation indices than age matched controls.
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From page 187... ...
(1995b) also exposed lymphocytes from women with silicone breast implants, normal controls, and women with defined connective tissue disease or fibromyalgia to three mitogens and colloidal silica.
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From page 188... ...
The authors reported increased proliferation of T-cells from women with breast implants on exposure to an aqueous silicone gel extract. However, a standard stimulation index was not given; instead, stimulation in the women with implants was compared to stimulation in the control group, and the difference in stimulation between the groups was much less than twofold.
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From page 189... ...
In general, studies addressing these issues are limited, and the technical problems associated with available studies are substantial. In view of these factors, the committee concludes that studies supporting a consistent pattern of marked T-cell activation or sensitization against autologous self-antigens or silicone in patients with silicone breast implants are inconsistent and unconvincing.
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From page 190... ...
In prolonged tissue exposures, as is the case with silicone breast implants, chronic inflammation seems to be the most relevant process. Accumulations of lymphocytes and monocytes, which later differentiate into macrophages, characterize chronic granulomatous reactions.
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From page 191... ...
Silicone implants eventually become walled off by the formation in vivo of a fibrous capsule, which is a normal element of the response to a foreign body. Contracture of the capsule can become a problem in some patients with silicone breast implants, as discussed in Chapter 5.
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From page 192... ...
(1993) examined anti-collagen antibodies in 46 women with silicone breast implants (2 women with previously diagnosed connective tissue disease, 38 symptomatic women, 6 asymptomatic women)
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From page 193... ...
Using this assay, these workers concluded that antisilicone antibodies were increased in women with silicone breast implants, and moreover, that the highest levels of antisilicone antibodies were found in implant recipients whose implants had ruptured. A control group of symptomatic women without breast implants was lacking, and whether the women studied were symptomatic or not was not reported.
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From page 194... ...
This is a non-silicon-containing compound; it is unlikely that it has any antigenic similarity to PDMS or other breast implant silicone compounds. In an early abstract report of APA testing of 97 symptomatic women with silicone breast implants, 19 asymptomatic women with implants, 23 healthy controls without implants and 15 women with classical connective tissue disease without implants, APA positivity was related to severity of illness (Tenenbaum et al., 1993a)
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From page 195... ...
(1999) in an abstract reported that APA assay results from the United States and the Amsterdam Red Cross Blood Transfusion Services Central Laboratory in 24 women with silicone breast implants undergoing explantation matched completely.
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From page 196... ...
In summary, the data on immunoglobulin levels are inconsistent, but a controlled study of an apparently random group of women did not find elevations in women with breast implants compared to matched controls. In this connection, several groups are currently in the process of studying whether subjects with silicone breast implants are more likely than the general public to develop multiple myeloma, a lethal malignant proliferation of monoclonal plasma cells considered to be a cancerous condition.
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From page 197... ...
The committee finds that there is conclusive evidence that some silicones have adjuvant activity, but there is no evidence that this has any clinical significance. The committee has also concluded that evidence from experimental studies of the immunology of silicone does not support, or lend biologic plausibility to, associations of silicone breast implants with immune related human health conditions.
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