CD4 and idiopathic CD4 lymphocytopenia: Idiopathic CD4 lymphopenia (ICL) is a rare syndrome defined as a CD4 T-lymphocyte count of less than 300 cells/μL or less than 20 % of total T-cells on more than one occasion in the absence of HIV infection and other secondary causes associated with depressed levels of CD4 T-cell [1].