Because lymphocytes make up a relatively small proportion of white blood cells, ----.
A) lymphocytopenia is an abnormally low lymphocyte count – below 1,500 cells per microlitre of blood in adults
B) the two main types of lymphocytes are Blymphocytes, also called B-cells, and Tlymphocytes, also called T-cells
C) a reduction in their number may not cause a significant decrease in white blood cell count
D) lymphocytopenia can be caused by a variety of diseases and conditions
E) people who have low T-lymphocyte counts usually have more severe lymphocytopenia than people who have low B-lymphocyte counts