Effect of antilymphocyte antibody in systemic lupus erythematosus on in vitro Ig synthesis

Systemic lupus erythematosus sera inhibit antigen presentation by macrophages to T cells

Several reports have demonstrated that systemic lupus erythematosus (SLE) patients have a decreased response to exogenous antigens both in vivo and in vitro. We examined the effects of SLE sera on macrophage (M phi) antigen-presenting functions. M phi from normal donors were pulsed with tetanus toxoid antigen in the presence of SLE or normal human serum (NHS), fixed in paraformaldehyde, and incubated with autologous T cells. Of 16 SLE sera tested, 11 inhibited the T-cell proliferative response (measured by [3H]thymidine uptake) compared to control NHS; mean percentage inhibition was 53 +/- 23%. This inhibition did not result from interference with antigen uptake by M phi and was found in both IgM and IgG fractions of the sera. There was a positive correlation between the amount of inhibition and the cytotoxic reactivity of the SLE sera against M phi as measured by Terasaki assay (r = 0.659, P less than 0.01). However, the presence and the amount of the inhibition did not correlate with serum immune complexes by Clq ELISA, serum anti-DR antibodies, or clinical disease activity of the SLE patients. We conclude that some SLE sera possess IgM and IgG antibodies reactive with M phi which affect M phi antigen-presenting functions, and might relate to decreased antigenic response in SLE patients.

Monoclonal murine anti-DNA antibody interacts with living mononuclear cells

A monoclonal mouse antibody, 4-B-5, that reacted with both single-stranded DNA (ssDNA) and double-stranded DNA showed direct reactivity and cell association with mouse thymocytes, as well as peripheral blood mononuclear cells. Absorption of 4-B-5 with peripheral blood mononuclear cells or with mouse thymocytes markedly reduced reactivity with both ssDNA and double-stranded DNA. However, treatment of mouse thymocytes or human T cells with DNase completely eliminated monoclonal anti-DNA reactivity with cells. The cellular reactivity was completely restored when monoclonal anti-DNA was incubated with DNase-treated cells in the presence of normal human serum. Normal human serum was found to contain 574 +/- 639 ng/ml of ssDNA. Coincubation or cell preincubation of mouse thymocytes with ssDNA produced a marked increase in 4-B-5 cell association. These findings indicate that mouse monoclonal anti-DNA can react with and can penetrate both mouse and human mononuclear cells, and that this reactivity may depend on the presence of cell membrane DNA on both types of target cells.

Changes in anti-lymphocyte and anti-Ia antibodies during pregnancy in systemic lupus erythematosus

Anti-lymphocyte antibodies reactive with monocyte-depleted lymphocytes, T cells, or B cells were studied in 43 nonpregnant and 23 pregnant systemic lupus erythematosus (SLE) patients. Anti-Ia specificity was assayed in an enzyme-linked immunosorbent assay system. No difference in mean lymphocytotoxicity was noted between pregnant and nonpregnant SLE patients; however, anti-Ia lymphocyte antibody associated with disease activity was lower (P less than 0.01) in pregnant than in nonpregnant SLE patients. Lymphocytotoxic or anti-Ia antibody activity did not reliably predict the outcome of individual pregnancies.

Cytotoxic anti-T cell antibodies in children with juvenile rheumatoid arthritis

The object of this investigation was to determine the prevalence of anti-T cell antibodies in 66 children with various connective tissue diseases. Anti-T cell antibodies were found in 43/44 juvenile rheumatoid arthritis (JRA) patients (mean cytotoxicity 15.0%) and in 10/10 children with systemic lupus erythematosus (mean cytotoxicity 20.0%), but in only 1/15 normal controls and in none of 12 children with other arthritides. There was no significant difference in mean percent cytotoxicity among the JRA subclasses. In the JRA patients, the percent cytotoxicity was positively correlated with the erythrocyte sedimentation rate (P = 0.01), but not with the presence or absence of rheumatoid factor, antinuclear antibodies, or immune complexes. The sera of 3 JRA patients repeatedly inhibited the stimulation of normal lymphocytes by mitogens and antigens by 47-99% (measured by the incorporation of 3H-thymidine into DNA) when added to the culture system in the first 24 hours; normal sera did not. Sera from patients with JRA have increased reactivity with mitogen-activated lymphocytes and T cells compared with unstimulated cells as determined by flow cytometry. The expression of the "JRA antigen" requires protein synthesis but not DNA synthesis or cell division. We conclude that the majority of patients with active JRA have cytotoxic anti-T cell antibodies and that in selected patients, these antibodies may play a role in regulation of the immune response.

The effect of plasmapheresis and drug immunosuppression on T-cell subsets as defined by monoclonal antibodies

The number of total T-cells and the number of helper/inducer T-cells decreased in 27 of 31 patients with immunologic disorders treated with plasmapheresis and drug immunosuppression. The number of suppressor/cytotoxic T-cells increased in the majority of patients. The helper/inducer to suppressor/cytotoxic cell ratio, which was initially elevated in 26 of 31 patients, decreased significantly in all but 2 patients after therapy. Ten patients were already on drug immunosuppression at the time plasmapheresis was started, and all 10 showed increased helper/inducer to suppressor/cytotoxic cell ratio despite their drug therapy. The helper/inducer to suppressor/cytotoxic cell ratio decreased in all ten patients after plasma exchange. The number and the percentage of total T-cells and helper/inducer cells decreased from prepheresis levels while the number and the percentage of suppressor/cytotoxic cells increased. Plasmapheresis, in combination with drug immunosuppression, was effective in decreasing the elevated helper/inducer to suppressor/cytotoxic cell ratio in disorders of the immune system. In contrast, patients on immunosuppressive drug therapy alone had persistently high immunoregulatory ratio.

T lymphocyte interaction with immunoglobulin G antibody in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease with multiple immune disturbances whose mechanisms remain unclear. We examined the interaction of antilymphocyte antibodies with cultured normal T lymphocytes. T cells were prepared by E-rosetting after petri-dish removal of adherent cells and cultured for 2-7 d in the presence of SLE sera or normal human sera. Cultured T cells were washed and sonicated, and the amount of cell-associated IgG was quantitated by radioimmunoassay or enzyme-linked immunoassay (ELISA) methods. T cells cultured with 27 of 39 SLE sera showed marked increments of associated immunoglobulin G (IgG) although this was not observed with sera from mixed connective tissue disease patients containing high titers of ribonucleoprotein antibody or normal donors. The effective factors for IgG association in SLE sera were absorbed with normal peripheral blood lymphocytes or T cells. Anti-T cell IgG cytotoxic activity strongly correlated with T cell IgG association (P less than 0.01). T cell-associated IgG was not removed by stripping of cell membrane IgG from living cells by acid buffer treatment; indirect immunofluorescence of cells fixed after 2-4 d of culture revealed cytoplasmic IgG staining. IgG anti-T cell antibodies appeared to associate inside the cell membrane or to penetrate into the cytoplasm of cells. T cell Fc receptor blocking by heat-aggregated IgG or anti-beta 2-microglobulin antibody did not alter IgG cell association. Since pepsin-digested SLE sera showed no T cell association activity, whole IgG antibody molecules appeared to be necessary for interaction with cultured T cells. In addition, reduction and alkylation of active SLE sera completely nullified T cell reactivity. When normal T cells were cultured with SLE sera showing marked IgG T cell association, viability of cultured T cells decreased rapidly after 4 d, which suggests that IgG anti-T cell antibodies were associated with cell destruction. IgG cell-associating antilymphocyte antibodies present in SLE sera may cause T cell disturbances in vivo and may be related to the lymphocytopenia present in SLE patients.