Monitoring and treatment of anti-D in pregnancy.

Prophylactic anti-D is a very safe and effective therapy for the suppression of anti-D immunization and thus prevention of haemolytic disease of the foetus and newborn. However, migration from countries with low health standards and substantial cuts in public health expenses have increased the incidence of anti-D immunization in many "developed" countries. Therefore, this forum focuses on prenatal monitoring standards and treatment strategies in pregnancies with anti-D alloimmunization. The following questions were addressed, and a response was obtained from 12 centres, mainly from Europe.

Induction of cytotoxic capacity by recombinant gamma interferon in human myelomonocytic leukaemia cell lines.

We have investigated the ability of human recombinant gamma interferon (IFN-gamma) to induce functional differentiation in three human myelomonocytic cell lines U937, RC2A, and ML-2. Treatment with IFN-gamma induced natural killer (NK) cell like cytotoxicity against K-562 cells in ML-2 and RC2A but not in U937. U937 and RC2A displayed a spontaneous antibody-dependent cell-mediated cytotoxicity (ADCC), which against nucleated target cells was significantly increased in U937 but not in RC2A after treatment with IFN-gamma. ML-2 did not display ADCC against nucleated targets either before or after IFN-gamma treatment, but lysed efficiently antibody-coated erythrocytes. All three cell lines displayed enhanced ADCC against erythrocytes after IFN-gamma treatment. Spontaneous phagocytosis of erythrocytes was seen in U937, and this was enhanced by IFN-gamma treatment, while ML-2 and RC2A were phagocytically inactive before and after treatment with IFN-gamma. The differentiated functions induced by IFN-gamma treatment in this panel of phenotypically closely related cell lines offers an interesting model for further studies on the IFN-gamma regulated gene expression. Moreover, the increased cytolytic capacity after exposure to IFN-gamma might have implications on the use of IFN-gamma for treatment of myelomonocytic malignancies. In such cases, IFN-gamma might even increase the aggressiveness of the tumour.

Inhibition of the activity of restriction endonucleases by spermidine and spermine.

Physiological concentrations (0.5-2.0 mM) of spermidine and spermine were observed to inhibit the digestion in vitro of plasmid pJDB 207 by the restriction endonucleases BamHI (EC 3.1.23.6), EcoRI (EC 3.2.23.13), HindIII (EC 3.1.23.20), HpaI (EC 3.1.23.23) and PstI (EC 3.1.23.31). The polyamines protected all the tested restriction sequences of DNA, since the activity of all endonucleases used was strongly inhibited. These results show the need for caution when using polyamines as experimental tools for recombinant DNA chemistry.

Spermidine and spermine stimulate the activity of T4-DNA ligase.

When the ability of T4-DNA ligase from E. coli NM 989 to form higher molecular weight polymers from linearized plasmid pJDB 207 was followed, it was observed that physiological concentrations (0.5 to 1.0 mM) of spermidine and spermine greatly stimulated the formation of these polymers. The effect had a strict specificity since 1,3-diaminopropane, putrescine (1,4-diaminobutane) and N1-acetylspermidine neither stimulated nor inhibited this activity of DNA ligase. The structural analogues of spermidine, methyl bis(guanylhydrazone) and 1,1'-[(methylethanediylidene)dinitrilo]bis(3-aminoguanidine) totally abolished the stimulatory effect of spermidine on T4-DNA ligase without affecting the enzyme's basal activity.