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We reported recently that a human protein, previously described as IL-1 inducible 26K factor (26K) or interferon-beta 2, was a potent growth factor for B cell hybridomas in vitro. Subsequently, it appeared that this protein was also identical with the lymphokine B cell stimulatory factor 2. Here we report that the levels of 26K are considerably increased during the early stages of acute infections of the central nervous system. This elevation in 26K titres was not observed in either chronic infections or in non-infectious diseases.

We report two patients with chronic encephalomyelitis due to Borrelia burgdorferi in whom the definite diagnosis was delayed because of atypical clinical features. The first patient presented with chronic spastic paraparesis, slight ataxia and nystagmus of several years' duration. A tentative diagnosis of multiple sclerosis was made in spite of important abnormalities of the CSF biological characteristics. The second patient presented with an acute aphasia and a bilateral Babinski's sign. He was thought to suffer from benign herpetic meningoencephalitis. Several months later, as the patient experienced relapses with cerebellar and spinal cord involvement, falsely positive tests for syphilis were found and an antibiotic treatment was given. High protein content, low glucose levels, pleocytosis and oligoclonal bands were observed in all CSF samples, but the definite diagnosis was based on the detection of serum and CSF antibodies against B. burgdorferi.

CSF and serum samples from 16 AIDS patients were tested for the presence of anti-HIV antibodies either by classical serological methods or by an immunoblot technique based on agarose gel isoelectric focusing and transfer of the specific IgG antibodies onto HIV antigens-loaded nitrocellulose sheets. This method enabled the demonstration of an intrathecal synthesis of anti-HIV oligoclonal IgG antibodies, often superimposed on diffuse polyclonal production, in 14 patients. The two negative cases were devoid of neurological signs or symptoms. However, two patients classified in stage II of the disease (asymptomatic infection) displayed an intrathecal synthesis of anti-HIV antibodies.

The authors describe various applications of an immunoblot technique which allows the qualitative determination of the specific antibody activity of oligoclonal IgG intrathecally synthesized in infectious diseases of the nervous system. After dilution of sera to the same IgG concentration as the paired CSF samples, 10 microliters of both fluids are applied side by side on agarose gel plates and isoelectrically focused. Precipitated IgG or specific IgG antibodies are then blotted onto a nitrocellulose sheet previously coated with either a rabbit anti-IgG antiserum or the antigen under study, respectively. The immunoblot is successively incubated with biotinylated anti-IgG antiserum and with the streptavidin-biotin-peroxidase complex before staining with 4 chloro-1-naphthol. This method was applied to samples from patients with subacute sclerosing panencephalitis, herpetic encephalitis, meningoradiculitis due to Herpes Zoster, neuro-AIDS, neurobrucellosis, meningoradiculitis or encephalomyelitis due to Borrelia burgdorferi, and tuberculous meningitis. In each case, specific oligoclonal IgG antibodies, superimposed or not on a diffuse polyclonal synthesis were detected in the CSF, but not, or more faintly, in the corresponding serum. This was taken as evidence for an intra-thecal synthesis of these antibodies. In contrast, when a "mirror effect" was observed, i.e. similar oligoclonal bands in both serum and CSF after dilution at the same IgG concentration, an intra-thecal synthesis was ruled out.