In fact, elevated serum level of β2-microglobulin or especially neopterin is more predictive of AIDS KS than is low CD4 lymphocyte count (Rabkin et al, 1990; Krämer et al, 1992), and cKS cases tend to have elevated levels of serum neopterin and β2-microglobulin (Touloumi et al, 1999; Brown et al, 2006). Here, CD4 is linked to Kaposi's sarcoma.