Absolute Lymphocytes Following Radiation For Prostate Cancer

I am looking for anyone who has had similar experience with their bloodwork following radiation treatment after removal of the prostate for cancer. The initial bloodwork after radiation showed a significant drop for red and white blood cells, which is normal. In about 6 months my CBC panel bloodwork showed red and white blood cell counts in the normal range. However, the Absolute Lymphocyte counts have stayed well below the normal range which is 850-3900 cells/uL. It has been 4 years since I completed 40 radiation treatments, and my Absolute Lymphocytes have remained in the 500-650 range. My doctors have no explanation as to why this is the only part of my bloodwork that has not returned to normal, and there apparently is no treatment for low Absolute Lymphocytes. Has anyone else experienced this issue? This is a real concern for me, as I may be going back for a second round of radiation in the near future, and I am worried about the effect on my Absolute Lymphocytes which are related to the immunity system.