Normal values for lymphocytes and causes of their increase/decrease in blood Normal values (number of cells per cubic millimeter of blood): 500 - 4,500. The main reasons for the decline in numbers: Immune deficiency. The main reasons for the increase in numbers: Viral and bacterial infections, Malignant blood disease. Lymphocytes make up 20-35% of all leukocytes. #lymphocytes #infection #Lowlymphocytes | About health and science in simple words | Facebook