C1q intrathecal synthesis can be performed using IgM reibergram

Abstract

INTRODUCTION C1q is a component of the classical complement system pathway and it has a functional link between the innate and adaptive immune system. Usually C1q is a blood-derived protein and it can be synthesized in the central nervous system. OBJECTIVE To demostrate the possibility to quantify C1q intrathecal synthesis by using the IgM reibergram. MATERIAL AND METHODS 64 paired cerebrospinal fluid (CSF) and serum samples from normal healthy people without blood-brain dysfunction were obtained. CSF and serum C1q was quantified by immunoenzimatic assay. All the results were plotted in the reibergram employed to determine IgM intrathecal synthesis. RESULTS The concentrations of C1q in CSF were two orders of magnitude lower than those in serum. C1q values increased with the increment of CSF/serum albumin concentration quotient (QAlb) (Figure 1) as a measure of the function ability of the blood-CSF barrier and the velocity of CSF flow suggesting diffusion of C1q from blood to CSF. Because the C1q molecular weight (400 kDa) is similar than IgM´s (800 kDa) the CSF and serum C1q values was plotted in IgM reibergram (Figure 2). CONCLUSIONS The strong positive correlation of C3 with QAlb suggests that a substantial portion of C1q in CSF originates from blood and the C1q complement system could be synthesized in the CSF and its quantities could be calculate by the corresponding IgM reibergram.