Antigen-specific B-cell function in human autoimmune thyroiditis

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Abstract
T-B cells from the peripheral circulation of patients with autoimmune thyroiditis were cocultured with sheep red blood cells (SRBC) or soluble human thyroglobulin (Tg), a self-antigen. The B-cell mitogen,Staphylococcus aureus, combined with macrophage-derived B-cell differentiating factor, inducedin vitro lymphoid activation and proliferation in the presence or absence of Tg or SRBC, which was monitored after 6 days by specific anti-Tg and anti-SRBC plaque-forming cell (PFC) responses (expressed as PFC per 106 T-B cells). In the presence of SRBC, significantly more anti-SRBC PFC (322±113, SE) were generated in normals (N=5) compared with autoimmune thyroiditis patients (58±36) (N=8) (P≦0.001), data consistent with an antigen-specific T-cell defect. Anti-Tg PFC, not detectable in normal controls, were observed in patients in the absence (111±41) and presence (171±64) of Tg (10–1000 ng/ml). However, variable responses were noted after such coculture experiments with Tg. Three patients demonstrated amplification of anti-Tg PFC, while three showed antigen-related inhibition of anti-Tg PFC. These data indicated heterogeneity of responses to Tg antigen in patients with autoimmune thyroid disease compounded by significantly depressed antigen-specific induction mechanisms.