Acute-phase C56-forming ability and concentrations of complement components in normotensive and hypertensive...

A prospective study of 61 women who were normotensive at booking revealed an increased incidence of C56-forming ability in those who later developed hypertension. Similar changes were found before delivery in a separate group of women admitted with latent hypertension and in each of 11 women with severe pre-eclampsia and a surviving fetus. The C56-forming ability, an acute phase feature, often preceded the hypertension and the findings suggest an indirect relation between complement changes and the mechanism causing hypertension in pregnancy. Concentrations of complement components in hypertensive and normotensive pregnancies were also compared with each other and with those of normal healthy non-pregnant women. The hypertensive patients had increased total alternative pathway function and higher factor B concentrations. The C56-negative sera from hypertensive patients tended to have C7 concentrations higher than normal whereas C56-positive patients had higher C5 concentrations. The aetiological and pathological implications are discussed.