Complement and lupus: old concepts and new directions

Neurologic, ophthalmic, and neuropsychiatric manifestations of pediatric systemic lupus erythematosus

BACKGROUND

Systemic lupus erythematosus (SLE) is an autoimmune, multisystem disorder with diverse manifestations. There are limited reports on the neuro-ophthalmic and neuropsychiatric findings in childhood SLE.

CASE REPORT

An 8-year-old patient with suspected SLE with a history of skin rash, joint pain, transient hematologic abnormality, headaches, seizures, and psychosis, presented with papilledema secondary to acquired, obstructive hydrocephalus.

DISCUSSION

SLE-related ocular and neuropsychiatric findings are reviewed. Proposed mechanisms for ocular and cerebral lupus include immune complex deposition, vascular thrombosis, and postinflammatory lesions.

CONCLUSION

The prevalent neurologic and neuropsychiatric complications of pediatric SLE require close follow-up and interdisciplinary management.

Vasculitic peripheral ulcerative keratitis

The onset of peripheral ulcerative keratitis in the course of a connective tissue disorder, such as rheumatoid arthritis, relapsing polychondritis, or systemic lupus erythematosus, may reflect the presence of potentially lethal systemic vasculitis. Moreover, peripheral ulcerative keratitis may be the first sign of systemic necrotizing vasculitis in patients with Wegener's granulomatosis, polyarteritis nodosa, microscopic polyangiitis, or Churg-Strauss syndrome. Although the exact pathogenesis of this severe corneal inflammation and destruction is not well understood, evidence points to a dysfunction in immunoregulation with immune complexes formed in response to autoantigens or to some unknown microbial antigen depositing in scleral and limbal vessels. These events lead to changes that are mainly responsible for the resulting tissue damage. In pauci-immune vasculitides positive for antineutrophil cytoplasmic antibodies, cell-mediated cytotoxicity may play an important role in the pathogenesis of peripheral ulcerative keratitis. Untreated systemic conditions such as those mentioned above may carry a grave prognosis for the eye and may also be life-threatening. Immunosuppressive therapy with corticosteroids and cytotoxic agents is, we believe, mandatory in the treatment of these multisystem disorders associated with vasculitic peripheral ulcerative keratitis.

Methods for assessing complement activation in the clinical immunology laboratory

Complement activation is a key component of the pathogenesis of immune-mediated tissue damage in many diseases. Assessment of complement activation in current practice is largely based on the measurement of intact C3 and C4 or the determination of complement haemolytic function. These parameters reflect activation only indirectly, are insensitive and open to influence by factors other than complement conversion. New approaches to evaluate complement activation directly using sensitive techniques have been developed, and several could be adopted easily in most laboratories. These concentrate on the detection of activation fragments, neoantigens or complexes that only arise as a direct result of complement activation. The wide application of these techniques in research and clinical practice would enhance our understanding of the pathogenesis of a range of inflammatory and infectious diseases.