Janet Pollock

Anti‐Rh(D) IgG Subclasses and Severity of Rh Hemolytic Disease of the Newborn

Abstract. The influence of anti‐Rh(D) IgG subclasses on the severity of hemolytic disease of the newborn was examined in 98 pregnancies. Disease was severe in 19 of 32 cases in which only IgG1 was detected, 40 of 63 cases in which IgG1 and IgG3 were found and 0 of 3 cases in which only IgG3 was detected. When both IgG1 and IgG3 anti‐D were present, hemolytic disease was more severe than when IgG1 alone was detected. The earliest onset of hydrops was at 20 weeks gestation in the IgG1+IgG3 anti‐Rh group, and at 27 weeks gestation in the IgG1 group.

Severe anti-C hemolytic disease of the newborn

Objective: Because of referral of a C-alloimmunized pregnant woman with a previous hydropic death whose fetus survived after four intraperitoneal transfusions, prevalence and severity of anti-C hemolytic disease of the newborn were investigated. Study Design: The numbers of C- or Ce-alloimmunized pregnancies in Manitoban women and their outcome for the 28-year period ending Oct. 31, 1990, were reviewed. The literature relating to C or Ce alloimmunization from 1944 to 1990 was surveyed. Results: In Manitoba for the period reviewed there were 120 pregnancies in 80 C- or Ce-alloimmunized women. Twenty-two ended in abortion and two in fetal death unrelated to anti-C or anti-Ce. Of the remaining 96, 33 fetuses of 32 pregnancies were affected but only eight (6.7%) required treatment after birth. None were severely affected. In the literature there are only three other reported deaths from C or Ce hemolytic disease; two of the three may have been the same patient. The prevalence of C or Ce alloimmunization reported in various series, including our own, ranged from 8.7 to 185 per 100,000 pregnancies. Conclusions: Because on rare occasions, C or Ce alloimmunization can cause severe hemolytic disease, criteria for investigative measures such as amniocentesis or cordocentesis do not differ from the criteria for instituting these measures in Rh o (D)—alloimmunized pregnancies.

Absorption of red cells from the peritoneal cavity of an hydropic twin.

A pair of monozygotic erythroblastotic twins, one with hydrops, the other without, were treated by intrauterine transfusion. The twins had a monochorionic, diamniotic placenta with gross surface vascular anastomoses; at birth their circulating blood was of a single composition. The composition established that the presence of ascites per se does not inhibit absorption of blood from the peritoneal cavity.

Low Protein Rh Immune Globulin (Rh IgG)

Abstract. After 16–32 months in solution at 4°C, ultracentrifuge and immunoelectrophoresis assays of five lots of low protein Rh IgG protein concentrations 3.9, 5.8, 4.1, 3.4 and 3.1%, revealed each lot to consist of a single unaggregated and unfragmented protein with an s20w constant of 6.5–7.3. The lots were 94.0–98.5% pure IgG. Autoanalyzer studies demonstrated no loss of anti‐D for 16–37 months except in one lot stable at 20 months which showed a drop from 363 to 298 μg/ml at 26 months. 125I antiglobulin measurements revealed a 23‐ to 40‐percent early loss of anti‐D with stability thereafter. Low protein Rh IgG cleared Rh‐positive cells from 11 Rh‐negative volunteers and protected 2,093 Rh‐negative women at risk of Rh immunization at least as effectively as standard Rh IgG. Low protein Rh IgG is a pure, stable, active, protective and economical agent for use in Rh prophylaxis.

Fetomaternal Transplacental Hemorrhage during Pregnancy and after Delivery

One third of very weakly Rh-immunized women show no increase in their level of Rh immunization during pregnancy and after delivery. Administration of 300 micrograms of Rh immune globulin at 6-week intervals does not alter the incidence of lack of progression of Rh immunization in such women. Thirty-three Rh-positive women who ultimately delivered ABO-compatible babies, had Kleihauer fetal transplacental hemorrhage (TPH) screening tests carried out at 2-week intervals during pregnancy and shortly after delivery. One third of the 33 women had no detectable TPH or a TPH of 0.01 ml of fetal red cells. We conclude that one third of weakly Rh-immunized women failed to show any progression of their Rh immune response during pregnancy or after delivery because they were exposed to too few fetal red cells (0.01 ml or less) to produce such a response.

AN ERROR IN RH TESTING IN PREGNANCY

Anti-D (anti-Rho) in the blood of two Rh-negative pregnant women was believed to be due to active immunization. In the first case, however, antibodies were no longer detectable 2 weeks later. In the second case they disappeared by the end of 31 weeks. It was discovered that both women had been given immune globulin (human) because of exposure to rubella. The globulin given to the first woman probably contained about 0.1 mug of anti-D per ml; that given to the second probably contained about 0.6 mug of anti-D per ml. Both babies were O Rh-positive. Both women were given Rh immune globulin after delivery. Both have completed a further pregnancy and no anti-D has been found on many tests. In tests carried out in 1971 all samples of immune globulin (human) examined contained anti-D, but usually in inconsequential trace amounts.