Figure 6.

The effect of soluble serum factors on T cell GM1 and LCK expression and T cell proliferation. T lymphocytes from lupus patients and controls were cultured for 72 hours with 50% sterile human serum. Some SLE sera were depleted of IgG using protein G–sepharose to remove autoantibodies. Cells were recovered and were fixed for confocal microscopy or were analyzed for LCK expression by flow cytometry. (A) Representative confocal microscopy images showing binding of CTB to GM1 in SLE and normal T cells cultured for 72 hours in autologous, normal, or SLE sera. Scale bars, 5 μm. N1, N2, sera from two different healthy controls; S1, S2, S3, sera from three different SLE patients. (B) Semiquantitation of CTB binding (MFI) of the images shown in A. (C) Representative experiment showing ex vivo expression of LCK (MFI) in T cells from SLE patients and controls. (D) Cumulative results showing LCK expression (MFI) in SLE and normal T cells after 72 hours in culture with autologous, normal, or SLE sera. (E) T cells recovered from incubation with 50% human sera were activated for 3 days with anti-CD3 and anti-CD28 and were pulsed with [³H]TdR. After 18 hours, cells were harvested and [³H]TdR incorporation was measured. Results are shown as a proliferation index (proliferation in autologous serum/proliferation in normal or SLE serum).