Sarcoidosis presenting as bilateral lacrimal gland swelling: a pediatric case report.

BACKGROUND: To describe a case of pediatric sarcoidosis which initially presented as papillary conjunctivitis before manifesting as bilateral lacrimal gland swelling without other known systemic involvement. CASE PRESENTATION: A 10-year-old female presented to the pediatric ophthalmology clinic with complaints of bilateral eyelid swelling, tearing and itching for approximately 1 month. Her history and exam were most consistent with allergic conjunctivitis, for which she was started on a standard topical regimen. Despite initial improvement, she re-presented with significantly worsened eyelid swelling and minimal allergic symptoms. Enlargement of the lacrimal glands were palpable at this time. Lacrimal gland biopsy was obtained which demonstrated noncaseating granulomas. Systemic workup did not reveal evidence of disease involvement elsewhere. CONCLUSIONS: Sarcoidosis in the pediatric population may present in a myriad of ways and is well-known to mimic other disease entities. We present a case of pediatric sarcoidosis which presented initially as papillary conjunctivitis before manifesting as bilateral lacrimal gland swelling without systemic involvement.

Autoreactive preplasma cells break tolerance in the absence of regulation by dendritic cells and macrophages.

The ability to induce Ab responses to pathogens while maintaining the quiescence of autoreactive cells is an important aspect of immune tolerance. During activation of TLR4, dendritic cells (DCs) and macrophages (MFs) repress autoantibody production through their secretion of IL-6 and soluble CD40L (sCD40L). These soluble mediators selectively repress B cells chronically exposed to Ag, but not naive cells, suggesting a means to maintain tolerance during TLR4 stimulation, yet allow immunity. In this study, we identify TNF-α as a third repressive factor, which together with IL-6 and CD40L account for nearly all the repression conferred by DCs and MFs. Similar to IL-6 and sCD40L, TNF-α did not alter B cell proliferation or survival. Instead, it reduced the number of Ab-secreting cells. To address whether the soluble mediators secreted by DCs and MFs functioned in vivo, we generated mice lacking IL-6, CD40L, and TNF-α. Compared to wild-type mice, these mice showed prolonged anti-nuclear Ab responses following TLR4 stimulation. Furthermore, adoptive transfer of autoreactive B cells into chimeric IL-6(-/-) × CD40L(-/-) × TNF-α(-/-) mice showed that preplasma cells secreted autoantibodies independent of germinal center formation or extrafollicular foci. These data indicate that in the absence of genetic predisposition to autoimmunity, loss of endogenous IL-6, CD40L, and TNF-α promotes autoantibody secretion during TLR4 stimulation.

Dendritic cells from lupus-prone mice are defective in repressing immunoglobulin secretion.

Autoimmunity results from a breakdown in tolerance mechanisms that regulate autoreactive lymphocytes. We recently showed that during innate immune responses, secretion of IL-6 by dendritic cells (DCs) maintained autoreactive B cells in an unresponsive state. In this study, we describe that TLR4-activated DCs from lupus-prone mice are defective in repressing autoantibody secretion, coincident with diminished IL-6 secretion. Reduced secretion of IL-6 by MRL/lpr DCs reflected diminished synthesis and failure to sustain IL-6 mRNA production. This occurred coincident with lack of NF-kappaB and AP-1 DNA binding and failure to sustain IkappaBalpha phosphorylation. Analysis of individual mice showed that some animals partially repressed Ig secretion despite reduced levels of IL-6. This suggests that in addition to IL-6, DCs secrete other soluble factor(s) that regulate autoreactive B cells. Collectively, the data show that MRL/lpr mice are defective in DC/IL-6-mediated tolerance, but that some individuals maintain the ability to repress autoantibody secretion by an alternative mechanism.