Complex sentence: Lymphocytic pleocytosis is involved in the initial stages of the disease, lymphocytes can number in the hundreds per mm3, while later on, lymphocyte levels have a tendency to return to equilibrium.
Split into simpler sentences: Lymphocytic pleocytosis is involved in the initial stages of the disease, lymphocytes can number in the hundreds per mm3. Later on, lymphocyte levels have a tendency to return to equilibrium.