The invention relates to in vitro method for quantitating the antibodies specific for High mobility group box I (HMGB1) contained in a sample, in particular a serum sample or a cerebrospinal fluid sample obtained from a HIV-infected subject, and the use of this method to monitor the human immunodeficiency virus (HIV) infection of a subject who is known to be infected with HIV. The invention also concerns a prognostic method of the state of progression of Acquired immune deficiency syndrome (AIDS) or the state of progression toward AIDS, in particular the state of progression or the state of progression toward neurological disorders associated with AIDS. Finally, the invention is also about method to determine the immune deficiency or level of immune activation of a HIV-infected patient.