If you've already had your own blood (or if someone you know has) injected into your CSF (or that of whomever you might be speaking) and there have been no untoward effects til now, then there probably won't be. If you're considering doing this for some reason (I can't imagine why anyone would, but I also am having difficulty imagining how this could happen accidentally) I would strongly recommend against it because of the dangers inherent in breaching any access to natural CSF reservoir.
This has been done in laboratory studies, with mice, and for reasons other than to see what might happen due to the presence of blood cells. During these studies the actual presence of small amounts of blood cells in the CSF did not, in and of themselves, cause any problems. Much would depend on the amount of blood and if it were contaminated with anything at all, which would most likely be the source of any problem.
Hopefully this answers your question. Good luck to you.
John Kenyon, EMT, CCT
Non-invasive cardiology tech, Emergency and Critical Care technician, Critical Incident Stress Mgmt. specialist