Antigen-specific oligoclonal IgG in AIDS-related cytomegalovirus and toxoplasma encephalitis

Objective - We retrospectively studied serum and cerebrospinal fluid (CSF) specimens from AIDS patients with either Cytomegalovirus (2 cases) or Toxoplasma gondii (5 cases) encephalitis. The samples, which had previously proved to be negative for total IgG oligoclonal bands (OCBs), were investigated for antigen-specific OCBs directed to the disease-related opportunistic agent. Material & methods - Paired serum and CSF samples from the given AIDS patients were considered. We undertook affinity immunoblotting of either virus- or protozoan-specific IgG onto antigen-coated nitrocellulose paper after protein separation by agarose isoelectric focusing (IEF). Results - Antigen-specific OCBs to the disease-related opportunistic agent were detected in serum and in CSF samples from all the patients. Conclusions - During overt AIDS, routine IEF methods may fail to detect OCBs, probably because nonspecific polyclonal hypergammaglobulinemia, which is typical of this disease, reduces their visibility. Our IEF/immunoblotting profiles are characterized by identical serum and CSF bands. The detection of antigen-specific OCBs may support the diagnosis of some opportunistic infections of the central nervous system in AIDS.