Expression and distribution of immunoglobulin G and its receptors in the human nervous system.

Recently, accumulating evidence has shown that several immunological molecules previously thought to be exclusively expressed by immune cells are also produced by nervous cells. Such molecules are thought to participate in the cross-talk between the immune and the nervous systems. IgG, an important immunological molecule, was traditionally thought to be produced by B lymphocytes only. In this study, extensive expression of neuron-derived IgG was detected throughout the nervous system. Relative quantification indicated that IgG was produced by neural cells at a low constant level. Transcripts of rearranged V-(D)-J segments and recombination activating genes-1 and -2 were also detected. Various IgG receptor types were also detected with distinct distribution patterns at different parts of the central and the peripheral nervous system. Given the widespread expression of IgG and its receptors, IgG most likely has an important biological function in the nervous system and might be classified as an immune mediator involved in neuro-immune crosstalk.