title: Isolation and characterization of a human nonspecific suppressor factor from ascitic fluid of systemic lupus erythematosus. Evidence for a human counterpart of the monoclonal nonspecific suppressor factor and relationship to the T cell receptor alpha-chain.
abstract: The monoclonal nonspecific suppressor factor (MNSF) is a lymphokine produced by a murine T cell hybridoma capable of suppressing Ab production by LPS-stimulated B cells. The existence of a human counterpart of MNSF, designated as the human nonspecific suppressor factor (hNSF), was likely because the anti-MNSF mAb (MO6) recognizes a similar suppressive activity in supernatants of Con A-stimulated human PBMC. By using the MO6 mAb, we investigated the presence of hNSF in the ascitic fluid of a patient with SLE. A small amount of cross-reactive hNSF was isolated from concentrated ascitic fluid fractionated with the MO6-affinity column, and a specific anti-hNSF mAb (P2) was produced. The hNSF eluted from the P2-affinity column could suppress up to 80% of the PWM-induced IgG production of human PBMC in a dose-dependent manner, even when added in late culture periods. Moreover, hNSF could inhibit proliferation of PBMC triggered by either PWM or Con A, which also implies an effect on T cells. On SDS-PAGE, the isolated hNSF resolved as a single peak of about 66 kDa and probably represents an aggregate of hydrophobic subunits. On reverse-phase HPLC, the bioactivity could be recovered from a single peak at 18.3 min. The suppression of IgG production induced by hNSF could be partly neutralized by preincubation with an anti-TCR-alpha mAb, whereas an anti-TCR-beta did not have any effect. Anti-TCR-alpha could also directly bind to the isolated nNSF, demonstrating some serologic relationship, as has been reported for several Ag-specific suppressor systems.
authors.affiliation: Third Division of Internal Medicine, Shimane Medical University, Izumo, Japan.
authors.forename: R M
authors.initials: RM
authors.lastname: Xavier
authors.forename: M
authors.initials: M
authors.lastname: Nakamura
authors.forename: T
authors.initials: T
authors.lastname: Tsunematsu
mesh_terms: D000328:Adult; D000818:Animals; D001202:Ascitic Fluid / Q000276:immunology*; D002851:Chromatography, High Pressure Liquid; D015180:Electrophoresis, Gel, Two-Dimensional; D005260:Female; D006801:Humans; D007526:Isoelectric Point; D008180:Lupus Erythematosus, Systemic / Q000276:immunology*; D051379:Mice; D008970:Molecular Weight; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000276:immunology; D013045:Species Specificity; D013491:Suppressor Factors, Immunologic / Q000737:chemistry / Q000302:isolation & purification*
chemical_list: D016693:Receptors, Antigen, T-Cell, alpha-beta; D013491:Suppressor Factors, Immunologic; C072169:monoclonal nonspecific suppressor factor