Activation of the alternative complement pathway accompanies disease flares in systemic lupus erythematosus during pregnancy.
OBJECTIVE
To assess the activity of systemic lupus erythematosus (SLE) during pregnancy and to distinguish it from preeclampsia.


METHODS
We prospectively measured the complement activation products Ba, Bb, SC5b-9, and C4d, as well as the conventional complement determinants C3, C4, and CH50, during pregnancy in 14 patients with SLE and 10 women with preeclampsia.


RESULTS
Four of the 14 SLE patients were considered to have disease flares, 3 occurring in the second trimester and 1 postpartum. In these patients, significant abnormalities of Ba, Bb, SC5b-9, and CH50 were noted. In contrast, measures of C4d did not distinguish between pregnant patients who had flares and those whose SLE remained stable. Although decreased values of C3 were rarely seen in the patients with stable disease, normal values of C3 during lupus pregnancy were not reliably associated with stable disease. Three of 10 non-SLE patients with preeclampsia had elevated levels of Ba; however, in each case, the CH50 level was close to or within the normal range. This was in sharp contrast to the findings observed in the 4 patients with active SLE, in whom high levels of plasma Ba were always associated with low CH50 values. Moreover, the ratio of CH50 to Ba was significantly lower in the patients with lupus flares than in the non-SLE patients with preeclampsia.


CONCLUSIONS
While a decline in the CH50 level alone could otherwise be attributed to decreased synthesis of complement components, these data demonstrate that ongoing activation of the alternative complement pathway can accompany disease flares in pregnant women with SLE.
Buyon
J P
JP
Department of Rheumatic Diseases, Hospital for Joint Diseases, New York, New York 10003.
Tamerius
J
J
Ordorica
S
S
Young
B
B
Abramson
S B
SB
D003167:Complement Activation / Q000276:immunology* / Q000502:physiology; D003181:Complement C4 / Q000032:analysis / Q000276:immunology; D015935:Complement C4b; D011415:Complement Factor B / Q000032:analysis / Q000276:immunology; D015941:Complement Hemolytic Activity Assay; D015938:Complement Membrane Attack Complex; D003170:Complement Pathway, Alternative / Q000276:immunology* / Q000502:physiology; D003171:Complement Pathway, Classical / Q000276:immunology / Q000502:physiology; D003165:Complement System Proteins / Q000032:analysis / Q000276:immunology; D003937:Diagnosis, Differential; D005260:Female; D006023:Glycoproteins / Q000032:analysis / Q000276:immunology; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000175:diagnosis / Q000276:immunology* / Q000473:pathology; D010446:Peptide Fragments / Q000032:analysis / Q000276:immunology; D011225:Pre-Eclampsia / Q000175:diagnosis / Q000276:immunology; D011247:Pregnancy; D011248:Pregnancy Complications / Q000175:diagnosis / Q000276:immunology* / Q000473:pathology; D011446:Prospective Studies
D003181:Complement C4; D015938:Complement Membrane Attack Complex; D006023:Glycoproteins; D010446:Peptide Fragments; C047610:SC5b-9 protein complex; D015935:Complement C4b; C032261:complement C4d; D003165:Complement System Proteins; D011415:Complement Factor B