Null cells in peripheral blood of normals and systemic lupus erythematosus

Network theory in autoimmunity. In vitro suppression of serum anti-DNA antibody binding to DNA by anti-idiotypic antibody in systemic lupus erythematosus

Regulation of serum anti-DNA antibody in systemic lupus erythematosus (SLE) by an antiidiotypic antibody was evaluated. Various sera from SLE patients in active and inactive states of their disease, as well as sera from normal individuals, were first completely depleted of anti-DNA and of DNA by affinity chromatography. The suppressive capacity of equimolar concentrations of the various depleted sera (blocking sera) on target lupus sera were determined. The target sera were from lupus patients with known DNA-binding capacity. Blocking sera from inactive SLE suppressed the binding of autologous anti-DNA antibody to [(3)H]DNA (n = 19,P < 0.01). Blocking sera from active SLE (n = 19), as well as human serum albumin, did not suppress. Sera from normal donors who had no contact with lupus patients or with lupus sera did not suppress (n = 14, P > 0.5), whereas those from normal donors who had contact with lupus patients or sera did suppress the binding (n = 5,P < 0.02). The anti-anti-DNA antibody suppressive activity in the inactive lupus serum was shown to be localized within the F(ab')(2) portion of immunoglobulin (Ig)G and could not be removed upon adsorption by normal human gammaglobulin. Furthermore, immune complexes could be detected by a Clq binding assay when the inactive lupus blocking sera were incubated with the anti-DNA antibody containing target sera. The specificity of the suppressive serum factor was shown by its inability to block the binding of tetanus toxoid to antitetanus antibody and its ability to block the binding of DNA to F(ab')(2) fragments of active lupus IgG. Regulation of serum anti-DNA antibody levels by anti-antibodies could induce and maintain disease remission in lupus patients and prevent disease expression in normals.

Tgamma cells in systemic lupus erythematosus. Variation with disease activity

Circulating T cells bearing receptors for the Fc portion of IgG (T gamma) were identified by sensitive immunofluorescent techniques with rabbit IgG b4 allotype/anti-b4 complexes. A twofold decrease in both proportion and absolute number of T gamma cells was found in patients with active systemic lupus erythematosus (SLE) relative to values obtained during disease remission. The reduction in T gamma cells was most evident in patients with severe hypocomplementemia. A deficit of T gamma cells in active patients was not demonstrated. The percentage of total T cells rosetting with sheep erythrocytes was reduced in peripheral blood of most patients regardless of disease activity status, but particularly during SLE exacerbation. Cells lacking intrinsic surface immunoglobulin, IgG Fc receptors, and receptors for sheep erythrocytes were increased. These cells, operationally termed null, exhibited an inverse linear relationship with T cells that was not apparent in regression analyses performed against other lymphocyte subpopulations. Such differences were not found for B cells and IgG receptor-bearing non-B/non-T cells which were present in normal proportions in virtually all patients. The origin and functional significance of these unusual lymphocyte subpopulation abnormalities are discussed.