sentences:  Too much can mean cell death but failure to propagate cytokines at all in remyelination results in a lack of debris clearance at a damaged axon site; this buildup of myelin and oligodendrocyte debris has been shown to inhibit the differentiation of Oligodendrocyte Precursor Cells.Specifically, cytokines promote TNFR2 and eventually TNF-alpha which plays a key role in OPC differentiation.It has also been shown that chemokines are involved in guiding immune cells to sites of axon lesions to facilitate inflammation and debris clearance as well as possibly guiding OPCs migration to lesion sites.