Neutralization by human serum samples of a transmissible agent isolated from the cerebrospinal fluid of neurological patients

A transmissible cytotoxic agent thought to be associated with one or more misfolded protein(s) was found in several cerebrospinal fluid (CSF) samples from neurological patients. Since some experiments carried out to identify this unusual infectious factor showed the block of its propagation by rabbit gammaglobulins (IgGs), the search for such an activity by human IgGs was programmed. Neutralizing assays carried out using human sera as IgGs source showed a blocking property displayed by: twenty serum samples from as many patients with a diagnosis of acute infection, two of ten sera from healthy subjects and four serum samples from patients with lupus erythematous (SLE). When neutralizing sera were tested on cell cultures in immunofluorescence assays for the serum ability to label specific protein( s), similar fluorescent pictures resulted in treated and control cells. On the other hand, the SLE serum samples disclosed a granulosity of the nuclear material of cytotoxic cells in accordance with the DNA apoptotic laddering reported in previous papers. Oxidative disorders, as suggested by the immunoblotting analysis of the antioxidant enzymes Mn-superoxide dismutase (SOD2) and heme-oxygenase 1 (HO-1), point to an alteration of the oxidative pathway among the causes of the DNA damage induced by the cytotoxic transmissible agent under study.

Propagation of a transmissible cytotoxic activity on cultures of human peripheral blood lymphocytes

Positive results were attained when human peripheral blood lymphocytes (PBLs) were investigated for their ability to propagate a transmissible cytotoxic activity (TCA) isolated on VERO cell cultures from a sample of cerebrospinal fluid (CSF) drawn from a woman with ischemic brain injury. In consideration of this finding it can be assumed that "in vivo" blood lymphocytes contributed to give rise to the TCA detected "in vitro" in the CSF inoculum.

Detection of a gliotoxic activity in the cerebrospinal fluid from multiple sclerosis patients

We recently showed that peripheral blood cell supernatants from multiple sclerosis (MS) patients, containing reverse transcriptase activity and retroviral RNA from the newly human identified multiple sclerosis retrovirus (MSRV), also secrete a cytotoxin which induces death of primary mouse cortical glial cells. We have hypothesized that macrophages could release this cytotoxin in the cerebrospinal fluid. The cerebrospinal fluid cytotoxicity from 166 patients with various neurological diseases (including MS patients) was tested on glial cells in vitro. Our bioassay shows that a glial cytotoxic activity is significantly present in cerebrospinal fluid from patients with relapsing-remitting MS at relapse. Since this cytotoxic activity seems to correlate with active cases of MS, it may represent a critical pathogenic factor in the neuropathology of MS.

The association of Shiga toxin and other cytotoxins with the neurologic manifestations of shigellosis

The neurologic symptoms in human shigellosis have often been attributed to Shiga toxin, although its exact role has not been determined. By use of a [3H] thymidine-labeled HeLa cell assay, cytotoxic activity was demonstrated in stool but not cerebrospinal fluid or serum from five patients with shigellosis presenting with seizures or encephalopathy. Bacterial isolates produced 16.0-88.2 CD50 (50% cytotoxic dose) of cytotoxin/mg of protein. The toxin activity in stool and the cytotoxic activity of the isolates were not neutralized by antiserum to purified Shiga toxin. DNA hybridization studies showed that Shigella isolates from these patients lacked the structural genes for Shiga toxin. The cytotoxin produced was also distinct from Shiga-like toxins I and II. Sonicates of the Shigella strains injected intraperitoneally into mice caused lethargy and lethality. The toxin activity was heat-labile and sensitive to trypsin, indicating that its active component is protein. Ultrafiltration and gel filtration chromatography showed a molecular mass of 100-125 kDa. Thus Shiga toxin production is not essential for the development of neurologic manifestations of shigellosis; other toxic products may play a role.

Cytotoxic activity of cerebrospinal fluids (CSF's) against lymphocytes and phagocytes: comparison of normal and systemic lupus erythematosus CSF's

Fifty cerebrospinal fluids (CSF), 24 normal, 26 from systemic lupus erythematosus (SLE) patients were tested for cytotoxic activity against human lymphocytes, granulocytes and monocytes. Normal and SLE CSF's frequently killed all 3 cell types. Lympho- and granulocytotoxins often reacted at both 4 degrees/24 degrees C, and at 37 degrees C. They were more active when no complement was added (p less than 0.01), whereas monocytotoxicity was complement-dependent (p less than 0.01). Normal CSF's more often contained cold-reacting lymphocytotoxins and SLE CSF's more often had warm-reacting monocytotoxins, but the differences were not significant (p = 0.03). Cytotoxins were easily absorbed to and eluted from lymphocytes and granulocytes, and when CSF's were toxic to both types of cells, the corresponding eluates usually retained this activity. Sometimes, only 1 type of cell was killed by the eluate, whereas cytotoxicity against another was retained by the corresponding supernatant. In SLE remarkable differences were noted between CSF cytotoxins and serum cytotoxins. The former were often more potent at 37 degrees C not requiring non-human complement. Preliminary characterization of CSF cytotoxins suggests they may be IgG, however, participation of non-Ig cytotoxic substances cannot be excluded.