An elevated absolute lymphocyte count is an indicator of infection, multiple myeloma or lymphocytic leukemia, notes MedlinePlus. Lymphocytes should make up approximately 20 to 40 percent of the white blood cells in a sample.
Viral infections, mononucleosis, chronic bacterial infections and infectious hepatitis are some of the infections associated with an elevated lymphocyte count, states MedlinePlus. Increased inflammation in the body also affects the number of lymphocytes circulating in the blood.
Multiple myeloma is a cancer that develops inside the cells responsible for identifying and destroying infectious organisms, explains Mayo Clinic. Cancerous cells build up in the bone marrow, preventing the plasma cells from producing helpful antibodies. Lymphocytic leukemia starts in the bone marrow, which is where lymphocytes are produced. Once malignant cells enter the bloodstream, the number of white blood cells in circulation tends to increase.
The medical term for a high lymphocyte count is lymphocytosis, as defined by Mayo Clinic. Adults are diagnosed with lymphocytosis when their absolute lymphocyte counts are significantly higher than 3,000 cells per microliter.
All lymphocytes start out in the bone marrow, but they can become B lymphocytes or T lymphocytes, reports KidsHealth. B lymphocytes identify potentially harmful organisms, while T lymphocytes destroy foreign invaders. Both types of lymphocytes help fight infection.