Complex sentence: Many cases point to a viral infection as the root cause of pleocytosis, in which the immune system produces antibodies against neuronal and vascular antigens, possibly connecting it to viral meningitis and Mollaret's disease.
Split into simpler sentences: Many cases point to a viral infection as the root cause of pleocytosis, in which the immune system produces antibodies against neuronal and vascular antigens. This evidence possibly connects it to viral meningitis and Mollaret's disease.