Soluble class 1 antigens (sHLA) in CSF and serum of patients with HIV infection.

sHLA are secreted by B and T lymphocytes upon activation. These antigens are present in serum and cerebrospinal fluid (CSF). The establishment of a sHLA index, IH = (CSF sHLA/serum sHLA)/(CSF albumin/serum albumin) helped us to define that values above 9.7 reflect an intrathecal synthesis of these proteins. IH was significantly increased in a group of patients with intrathecal production of IgG against HIV-1 (HIV) and directly correlated with the synthesis of such antibodies. Therefore, IH seems to be an index of lymphocyte activation in CNS.