Methods for the diagnosis and prognosis of immunosuppressive conditions are disclosed, involving the detection of a particular isoform of ferritin, placental ferritin (PLF), in patient samples such as sera or on peripheral blood lymphocytes. PLF is elevated in immunosuppressed patients at early stages of disease; by contrast, adult insoferritins are elevated at late stages of immunodeficiency. Depending upon the nature of the disease associated with the immunodeficiency, the elevated levels of PLF detected at early stages may remain elevated or diminish as disease progresses. Examples are described in which elevated levels of PLF were detected at very early stages of of HIV-infection. The elevated levels diminished as disease progressed from ARC to AIDS. By contrast, adult isoforms of ferritin became elevated at late stages of disease.