The Pathogenesis of Graves’ Disease

Graves' disease as immune reconstitution disease in HIV-positive patients is associated with naive and primary thymic emigrant CD4(+) T-cell recovery

OBJECTIVE

Immune restoration disease (IRD) can develop in HIV-infected patients following antiretroviral therapy (ART) initiation as unmasking or paradoxical worsening of opportunistic infections and, rarely, autoimmune phenomena. Although IRD usually occurs in the first months of ART during memory CD4 T-cell recovery, Graves' disease occurs as a distinctive late-onset IRD and its pathogenesis is unclear.

DESIGN

Seven patients who developed Graves' disease following ART initiation from the primary HIV care clinic at the National Institutes of Health were retrospectively identified and each was matched with two HIV-infected controls based on age, sex, and baseline CD4 T-cell count. Laboratory evaluations on stored cryopreserved samples were performed.

METHODS

Immunophenotyping of peripheral blood mononuclear cells (PBMCs), T-cell receptor excision circle (TREC) analysis in PBMCs, measurement of serum cytokines, and luciferase immunoprecipitation systems (LIPS) analysis for autoimmune antibodies were performed on stored samples for cases and controls at baseline and longitudinally following ART initiation. TSH/thyrotropin receptor (TSH-R) antibody testing was performed on serum from cases. Data were analyzed using nonparametric testing.

RESULTS

In comparison with controls, the proportion of naive CD4 T cells increased significantly (P = 0.0027) in the Graves' disease-IRD patients. TREC/10 PBMCs also increased significantly following ART in Graves' disease-IRD patients compared with controls (P = 0.0071). Similarly, LIPS analysis demonstrated increases in nonthyroid-related autoantibody titers over time following ART in cases compared with controls.

CONCLUSION

Our data suggest that Graves' disease-IRD, in contrast to early-onset IRD, is associated with naive and primary thymic emigrant CD4 T-cell recovery and inappropriate autoantibody production.

Euthyroid pretibial myxedema

OBJECTIVE

To describe a case of biopsy-proven pretibial myxedema in a man with normal thyroid function.

METHODS

We present the pertinent clinical and laboratory data for the current case and review previously published information on pretibial myxedema.

RESULTS

Our patient, a 53-year-old man, had the characteristic lesions of pretibial myxedema on the anterolateral aspects of his calves. Laboratory tests showed normal thyroid function. The thyroid-stimulating immunoglobulin value was above normal. No exophthalmos or goiter was present. This uncommon dermopathy is typically associated with Graves' disease, accompanied by clinical hyperthyroidism, ophthalmopathy, and goiter.

CONCLUSION

The pathogenesis of pretibial myxedema remains elusive. It is presumed to be an autoimmune phenomenon attributable to the presence of serum thyroid-stimulating immunoglobulin, although immunofluorescence studies have failed to demonstrate a direct role for such an immunoglobulin. Only two other cases of biopsy-proven pretibial myxedema in a euthyroid patient were found in the literature.