Hi Doctor, this may seem like a silly question, but i'd like to know. Can you please explain the difference, if indeed there is one, between CD4 % and Lymph % Can one be low and the other normal? Also, what exactly is Idiopathic Lymphocytopenia, how common is this?

CD4 cells are a subset of lymphocytes which are in turn a subset of total white blood cells (WBC). Thus when someone gets a CBC done, they will get results for total WBC, as well as the total number of lymphocytes and percent of lymphocytes. You can certainly have a normal lymphocyte percentage and still have very low CD4 cells. In HIV infection, what usually happens is that CD4 cells go down and CD8 lymphocytes go up. Thus the overall total may stay the same. Idiopathic lymphopenia or CD4 depletion syndrome is a rare syndrome that has recently been described. People were found to have opportunistic infections, low CD4 counts (<200), but no sign of HIV infection. It is still not clear what causes the CD4 count to be low.

MH