Complement activation in fetuses: assessment by the levels of complement components and split products in cord blood.

The whole complement activity (CH50) and concentrations of components (C1q, C3, and C4) and C3 split product (C3d) were determined in the cord blood of 172 newborns between 16 and 42 weeks of gestation. Histological examination of their placentas revealed that the extent of complement activation was significantly higher in those with some degree of inflammation in the amnion than in those with normal amnion. The correlation between the complement levels and gestational age was higher in those with no amnionitis. In some cases the level of C3d at an early gestational age was as high as that in adults. The C3 activation system seems to be well developed even before week 25 of gestation. Among the complement components, C3d was the most sensitive indicator of placenta inflammation. As placenta inflammation may reflect intrauterine infection, the measurement of C3d levels may be of diagnostic value.

Glomerular immune deposits in kidneys from patients with no clinical or light microscopic evidence of glomerulonephritis. Assessment of the influence of autolysis on identification of immunoglobulins and complement.

Using a direct fluorescent staining technique, immunofluorescent microscopy (IFM) demonstrated glomerular deposits of IgG and IgM and/or fractions of complement in kidney tissue from 24% of 33 patients examined post mortem and in 39% of kidney biopsies obtained from 23 patients on lithium treatment. All the patients investigated had a normal blood pressure. There was no evidence of glomerulonephritis (GN) neither clinically, at light microscopy, nor on laboratory investigation. These "spontaneously" deposited immunoglobulins and complement fractions in glomeruli will obviously by demonstrated in kidney biopsies from patients with GN, even though they bear no relation to the disease. This will therefore preclude an immunopathological classification which relates to histological and clinical findings. A control study of the IFM findings in glomeruli on 13 surgically removed kidneys showed optimal identification and no further glomerular deposition of immunoglobulins during the 72 hours following nephrectomy, at temperatures below 10 degrees C. Clq and C3 were less stable and were only demonstrated with certainty up to 24 hours after nephrectomy.