[Are C1q binding immune complexes appropriate as markers for infected ventriculo-atrial shunts?]

Routine C1q-fluid phase radioimmunoassay identified high levels of C1q-binding immune complexes in 3 patients with infected ventriculoatrial shunts (VAS). Accordingly, C1q-binding activity was prospectively studied in additional 36. VAS patients to learn whether the observed immune complex activity was secondary to bacterially contaminated shunts or was a normal sequela of continuous intravenous infusion of cerebrospinal fluid into the vascular space. Pathological levels of C1q-binding activity were detected in only 3 out of 32 patients without evidence of shunt infection. However, extremely high C1q-binding activities were measured in 4 more patients with proven shunt infections. Thus, elevated levels of C1q-binding immune complexes correlate with infected VAS. As shunt infection is otherwise difficult to detect, serum C1q-binding activity may prove to be a valuable diagnostic tool for this condition.