Anti-Ia Reactivity in Sera from Patients with Systemic Lupus Erythematosus

Antileukocyte antibodies in sera from patients with systemic lupus erythematosus (SLE) were characterized by determining cross-reacting specificies with the antigens defined by OKT3, OKT4, OKT8, OKM1 and anti-Ia hybridoma antibodies (Abs). T cells were prepared by sheep erythrocyte (E) rosetting after removal of adherent cells. T cells, or non-T cells, were preincubated with SLE sera at 4°C and then with monoclonal Abs. Binding by specific monoclonal Abs was assessed by two methods: rosetting with ox erythrocytes conjugated with goat anti-mouse IgG and also in the fluorescence-activated cell sorter using fluorescein isothiocyanate-conjugated goat anti-mouse IgG. Using the rosetting method, we found that sera from SLE can block the binding of monoclonal mouse hybridoma anti-Ia Abs to T cells; the blocking of other monoclonal Abs was not consistent. Using fluorescence-activated cell sorter analysis, preincubation with SLE sera lowered the intensity of staining and total percentage of either T or non-T cells stained by monoclonal anti-Ia Abs. Blocking of anti-Ia Abs binding by SLE sera was not histocompatibility leukocyte antigen (HLA)-DR restricted and was not due to Fc receptor binding. These results indicated that antibodies in SLE sera react with structures contiguous to or identical with Ia determinants. Anti-Ia activities in SLE sera correlate with SLE disease activity. In addition, there was a significant negative correlation between anti-Ia blocking activity in the sera and the percentage of Ia-positive T cells in the blood of SLE patients. Antibodies in SLE sera with anti-Ia blocking activity may play an important role in immune dysregulation in SLE patients.

Click on an image below to see the page. View PDF of the complete article

page 17

page 18

page 19

page 20

page 21

page 22

page 23

page 24