Complement in hemolytic disease of the newborn.

demomnstrated loiv conncenntrat.ionns of complement shortly after the occurrennce of hemobytic crises inn paroxysmal cold hemogbobinnuria. Young, et al.4 foumnd that the complement bevels of dogs dropped sharply aind rose fain-ly promptly to normal values after the production of intravascular hemobysis by the adminnistrationn of imncompatible blood transfusions. Dacie amid de Gruchy5 reported ah)mnormally loiscomplememnt comicentrat.iomns inn four patients w-ith acquired hemolytic annemia. Jordan amid his associates6 founnd the complement len-el to remainn is-ithinn normal limits inn one case of paroxysmal cold hemogbobinnuria. We han-c i)eemn abbe to fimnd four cases of paroxysmal (-old hemogbobinnuria reported inn 1932’ . inn which complemennt len-cbs is-crc found to be extremely lossor en-cnn aI)scmnt. Inn nieis of the demomistrated activity of complement. inn ccrt.ainn hemolytic anemias amid mamny immunnobogic reactions, the present study is-as unidertaken to determinne if there is anny change inn the hemobytic actin-ity of complement in hemolytic disease of the miens-born due to anti-D (aint.i-Rho) isoimmunnizationi. We also attempted to determinne if compbemennt is consumed svhen imncomplete amnti-D annt.ibodies act inn n-it-ro.