Immune thrombocytopenia: effects of maternal gamma globulin infusion on maternal and fetal serum, platelet, and monocyte IgG

The role of P-selectin in the immune destruction of platelets

Antibody-mediated platelet destruction is a poorly understood process, although several lines of evidence suggest that Fcgamma receptor (FcgammaR)-expressing splenic macrophages may be involved. In this study, chemiluminescence (CL) was used to measure the in vitro metabolic response of human monocytes to platelets sensitized with a human immunoglobulin (Ig)G1 recombinant antihuman platelet antigen-1a (anti-HPA-1a) antibody (B2G1; P-hrIgG1). CL responses were inhibited, but not abrogated, in the presence of 10 micro g/ml human IgG or murine IgG2a, suggesting that FcgammaRI was principally involved. Experiments to determine the effect of Fab fragments to FcgammaRII found that CL responses to P-hrIgG1 were significantly enhanced, indicating that crosslinking of monocyte FcgammaRII by platelet-bound hIgG may modulate concomitant activation by FcgammaRI. Several observations suggested that the CL responses to P-IgG were dependent on the activation of resting platelets during their co-culture with monocytes and their subsequent P-selectin-mediated adhesion. First, the magnitude of the CL response was related to the level of P-selectin expression following platelet activation with alpha-thrombin. Second, CL responses were inhibited in the presence of antibodies that block the binding of P-selectin to P-selectin glycoprotein ligand-1 but not when platelets were pretreated and then washed. Third, the addition of anti-HPA-1a to monocytes from HPA-1a-negative donors preincubated with HPA-1a-positive platelets resulted in rapid CL responses. Finally, PGI2 inhibited the CL response to resting P-hrIgG1. Thus, evidence is presented that the interaction of human monocytes with P-hrIgG1 is mediated by FcgammaRI, modulated via FcgammaRII, and enhanced by the presence of P-selectin on the platelet membrane.

Clinical uses of intravenous immunoglobulin in pregnancy

The obstetric literature contains numerous reports of IVIG therapy for various conditions encountered during pregnancy. The mechanisms of action of IVIG are uncertain and may vary depending on the specific disorder. Immunoglobulin G infusions appear to be well tolerated by the parturient. The occurrence of major and minor side effects is uncommon, and infectious morbidity is low. Further research will be necessary to elucidate the specific mechanisms of action of IVIG in certain disease states. Determining the exact "therapeutic agent" in IVIG for each specific disease state may allow for a more tailored approach to treatment (i.e., isolation or production of the particular antibody). Outcome assessment, long-term positive and negative effects, cost-benefit analysis, and effects on fetal and neonatal immune function require further study through randomized trials.

Clinical uses of intravenous immunoglobulin in pregnancy

Intravenous immunoglobulin was licensed for use in the United States in 1981. Currently, there are only a few Food and Drug Administration-labeled indications for intravenous immunoglobulin, but up to 50 "off-label" uses are reported in the literature. The obstetric literature contains numerous reports on intravenous immunoglobulin therapy during pregnancy. This article reviews the properties, pharmacokinetics, mechanisms of action, and side effects of intravenous immunoglobulin, as well as the reported uses of intravenous immunoglobulin during pregnancy.

Pregnancy in idiopathic aplastic anemia (report of 10 patients)

This paper reports on 6 patients with severe, 2 with moderate and 2 with mild aplastic anemia who had a total of 18 pregnancies after the diagnosis. All four pregnancies that occurred during the active state of severe and moderate aplastic anemias were electively terminated. Two out of 14 pregnancies that occurred during the long-term remission were electively terminated for non-medical reason, two spontaneous abortions occurred and 10 live births were seen. All offspring were healthy at follow-up. During pregnancy the circulating blood cell levels decreased in 1 out of 6 pregnancies in patients who were in remission from mild and moderate aplastic anemias, and in 4 out of 8 pregnancies in patients who were in remission from severe aplastic anemia. In all 5 cases that showed a relapse during pregnancy the remission recurred following the termination of pregnancy. The data presented suggest that aplastic anemia in long-term remission can unpredictably relapse during pregnancy, but its final outcome appears not to be affected by pregnancy. Furthermore, there is no correlation between the pre-pregnancy clinical course and the events during pregnancy. The outcome of pregnancy during the remission of aplastic anemia seems beneficial, and spontaneous delivery should be preferred.