Intrathecal production of antibodies against Toxoplasma gondii in patients with toxoplasmic encephalitis and the acquired immunodeficiency syndrome (AIDS).

We attempted to determine whether patients with the acquired immunodeficiency syndrome (AIDS) and toxoplasmic encephalitis produce Toxoplasma antibodies in the central nervous system, and whether these antibodies would be useful for diagnosing toxoplasmic encephalitis. Thirty-seven patients with AIDS and toxoplasmic encephalitis and 11 patients with AIDS alone were studied. All patients had serum IgG but not IgM Toxoplasma antibodies. Twenty-three of the patients with AIDS and toxoplasmic encephalitis had Toxoplasma antibody in cerebrospinal fluid compared to none of the patients with AIDS alone. Of the patients with AIDS alone who had serum antibodies to T. gondii, none had Toxoplasma antibodies in cerebrospinal fluid. Production of antibodies in the central nervous system was seen in 11 of 16 patients with AIDS and toxoplasmic encephalitis but not in 4 patients in the control group who only had Toxoplasma antibody in their cerebrospinal fluid. These results suggest that production of T. gondii antibodies in the central nervous system may be diagnostic of toxoplasmic encephalitis.