Routine antenatal Rhesus D immunoglobulin prophylaxis: the results of a prospective 10 year study.

OBJECTIVE: To assess the clinical and financial impact, and identify the problems, of providing routine antenatal RhD immunoglobulin prophylaxis for Rhesus D negative nulliparae. DESIGN: A retrospective (1980-1986) and prospective (1987-1996) comparison between two similar populations, one population with nulliparae offered routine RhD immunoglobulin 500 IU prophylaxis at 28 and 34 weeks of gestation part way through the study period, and the other population not offered prophylaxis at any time. SETTING: Obstetric units in two counties (three health districts) with similar annual numbers of maternities and the Regional Blood Transfusion Service antenatal serology laboratory. PARTICIPANTS: Non-sensitised Rhesus D negative pregnant nulliparae. INTERVENTIONS: Intramuscular RhD immunoglobulin 500 IU at 28 and 34 weeks of gestation to eligible women booked for confinement in one county; the intervention not offered in the other county. MAIN OUTCOME MEASURES: 1. Rhesus D sensitised second pregnancy rate; 2. success in providing prophylaxis to eligible women; 3. serology laboratory activity changes; 4. potential savings from the prophylaxis programme. RESULTS: Prophylaxis significantly reduced iso-immunisation in the next pregnancy when compared with historical (OR 0.28, CI 0.14-0.53; P < 0.0001) and contemporary controls (OR 0.43, CI 0.22-0.86; P = 0.02). However, success at achieving comprehensive prophylaxis was disappointing, with only 89% of eligible women receiving the first injection, 74% both injections, and for only 29% were both at the correct gestation. Fifty-two percent of women delivered after 40 weeks of gestation, beyond the period of adequate prophylaxis protection. The savings in antenatal interventions, neonatal care and possible long term ill-health that result from very preterm birth should be considerable. CONCLUSION: Routine prophylaxis for nulliparae significantly reduces the incidence of sensitised next pregnancies with consequent savings, and its adoption nationwide should be encouraged. A programme offering antenatal prophylaxis for all Rhesus D negative women is unlikely to be economic. Improvement in uptake of prophylaxis is needed; alternative administration strategies should be explored.

Neonatal alloimmune thrombocytopenia due to anti-HPA-5b (Br(a), Zav(a), Hca): the importance of third-generation platelet antibody detection techniques, a case report.

Investigation of the maternal serum in a case of suspected alloimmune neonatal thrombocytopenia by conventional, second-generation platelet serological assays (platelet radioactive antiglobulin test [PRAT], platelet suspension immunofluorescence test [PSIFT] and solid-phase adherence assay (SPAA, 'Capture-P') demonstrated only the presence of HLA class-I antibodies of limited specificities: no platelet-specific antibodies were detectable. The use of a third generation, glycoprotein capture assay (monoclonal antibody-specific immobilization of platelet antigens, MAIPA) revealed the additional presence of anti-HPA-5b with a titre of 1 in 32. Despite this relatively high titre, and the fact that it was able to induce a prolonged thrombocytopenia, this antibody was not detectable by conventional assays. In view of these findings we conclude that the use of MAIPA is essential when investigating cases of suspected alloimmune neonatal thrombocytopenia.

Post transfusion septicaemia 1980-1989: importance of donor arm cleansing.

AIMS: To determine the prevalence of Pseudomonas fluorescens on the arms of blood donors, and to elucidate one possible cause for its predominance (60% of cases during 1980-89) in exogenous post transfusion septicaemia (PTS). METHODS: Skin swabs were taken from the arms of 782 blood donors and cultured on to heated blood agar. After incubation, Oxidase reagent and the Gram stain were used to select non-fermentative Gram negative rods, which were then subcultured and identified using the Analytical Profile System (API) 20 NE system. RESULTS: Non-fermentative Gram negative rods were found on the arms of 11.7% of donors, Pseudomonas spp on 1.0%, and Ps fluorescens on the arms of 0.3% of donors. CONCLUSIONS: This evidence emphasises the absolute requirement for efficient skin cleansing of blood donors' arms to minimise the risk of exogenous PTS.

In-utero intravascular transfusion of the fetus for the management of severe Rhesus isoimmunization--a reappraisal.

Ten fetuses, severely affected by Rhesus (D) haemolytic disease, received one to three intravascular blood transfusions at between 18 and 30 weeks gestation, with the use of fetoscopically guided needles into one of the umbilical cord vessels. Although the technique was successfully accomplished in all cases, the fetal response to the procedure was varied. Only two fetuses survived beyond the neonatal period, and one child subsequently died principally because of the problems resulting from premature delivery. The reason for the low rate of survival has been explored and the continued use of the method described is now questioned.

Pre-transfusion non-invasive quality assessment of stored platelet concentrates.

The Platelet Monitor System has been designed to assess routinely prepared platelet concentrates (P.C.) during storage. The system is based upon observations of changes in light transmission induced by platelets in intact packs. It is practical, provides constant gentle agitation for P.C., and non-invasively give continuous semi-quantitative evidence of the probable numbers of discoid platelets within each pack. The information yielded correlates both with established in vitro parameters of platelet behaviour, and with in vivo survival of platelets in normal healthy volunteers. The device safely provides the Blood Banker with the means to achieve on-going assessment of methods and improvements--or failings--in P.C. production. To the clinician it offers information throughout and even beyond present arbitrary storage limits, about which P.C. are likely to be of least or greatest value to a thrombocytopenic patient.

Blood group antibody screening tests during pregnancy.

In a 2-year period 667 sera from approximately 70,000 (0.95%) antenatal patients were found to contain 726 atypical red blood cell antibodies. Overall, 66% of the immunized mothers were rhesus (D) positive. Apart from four antibody specificities to rhesus system antigens, knowledge of the rhesus (D) group gave no guide to the ability of the patients to form any of the remaining 21 specificities encountered. Of the 726 antibodies 221 (30%) were not detected in the initial sample tested and 50 of the 92 patients who produced antibodies during pregnancy had not developed detectable antibody when they were sampled at 28 weeks. The significance of these late onset antibodies is discussed both in relation to the risk of haemolytic disease in the newborn and transfusion reactions in the mother. An optimum protocol for testing is defined which takes account of antibody production during the pregnancy and use of this protocol constitutes an attempt to combine maximum clinical safety with minimal consumption of resources.

Separation of plasma from whole blood by membrane filtration in oscillatory flows.

This paper describes the performance of a microfiltration plasmapheresis unit operating with reversing oscillatory flows. The device consists of a flat channel duct between cellulose nitrate membranes and was used to extract plasma from anticoagulated fresh whole bovine blood. Measurements were made of plasma flux, haematocrit concentration, haemolysis and protein sieving coefficients. The effects on plasma flux are reported for alterations in the stroke and frequency of flow pulsations, transmembrane pressure, membrane properties and blood throughput. It was found that the imposition of oscillatory flows enhanced the plasma extraction rate by a factor of 3, producing about 0.9 litre/min/m2 membrane.

Comparative trial of six methods for the detection of CMV antibody in blood donors.

Six techniques were compared to find the most suitable method for determining the cytomegalovirus (CMV) antibody status of blood donors. Five hundred and ninety-six random sera were tested by immunofluorescence (IF), complement fixation (CFT), two enzyme linked immunosorbent assays (ELISA), a commercial indirect haemagglutination test (IHA)--used as supplied, and a locally devised micromodification of the same IHA test. Five hundred and thirty-five sera shared total agreement of results by all tests. The ELISA tests were the most discordant with other methods (10.5% discordancies both positive and negative). IF and CFT correlated well with other tests (0.8% discordances each) but for different reasons are unsatisfactory for donor screening. The IHA test used as supplied and its micromodification gave the most consistent results (0.8% and 0.5% discordancies respectively). The micromodification is easy to perform and read; it compares very favourably with CFT and IF for material costs and expertise required, and readily lends itself to the testing of large numbers of sera in a reasonable time. Within certain provisos the micro-IHA technique described is recommended as the most suitable test for blood donor screening.

HLA and keratoconus.

HLA-A and -B antigens were determined in 64 Caucasoid patients with keratoconus. A highly significant increase in the frequency of HLA-B5 was found among the patients. Thus keratoconus is the third eye disease after recurrent herpetic keratitis and Behcet's disease showing an association with HLA-B5.

Comparison of platelet storage in PL146 and PL732 plastic packs: preliminary in vitro studies.

This paper is a preliminary report of in vitro studies comparing platelet storage in the new polyolefin PL732 packs with the present polyvinyl PL146 packs. The parameters used to assess platelet viability in these studies were the recovery from the hypotonic stress test (HST) and the pH. The effect of the mass of concentrate was assessed by preparing 20 g, 35 g and 50 g packs. The method of agitation was tested comparing a vertical rotator with a flat-bed, rocking agitator. In all the subgroups the PL732 packs fared better than the PL146 packs in terms of HST recovery and pH. The 35 g and 50 g packs were statistically inseparable but the 20 g packs were significantly worse both in PL732 and PL146. The vertical rotator augmented the beneficial effects of the PL732 plastic especially in terms of pH. The 35 g and 50 g packs in PL732 on a vertical rotator gave results after 5 days storage at 22 degrees C which were vastly superior (p less than or equal to 0.001) to the 35 g and 50 g packs in PL146 after only three days storage. Thus it would appear that the use of PL732 packs might enable the storage life of platelet concentrates to be increased to five days. Further in vivo studies are to be undertaken to ensure these in vitro improvements benefit the patient.

HLA antigens in East African Black patients with Burkitt's lymphoma or nasopharyngeal carcinoma and in controls: a pilot study.

A pilot study is reported of HLA-A, B, and C antigens in 141 East African Blacks comprising patients with Burkitt's lymphoma or nasopharyngeal carcinoma, either with active disease or in long-term remission, together with comparable controls. This study forms part of a wider program investigating host factors in these diseases. A protocol was selected for optimal testing of cells processed and cryopreserved between 1972 and 1976, largely under field conditions, which employed a two-color fluorochromasia typing procedure. Antigen distribution and computed haplotype frequencies in the total unrelated population are given. New findings include an approximately equal frequency of Aw23 and Aw24, a high (18%) incidence of Bw21, and the gametic associations of Aw36 with Bw44, and Aw30 with Bw45. Of the major group of B15-related antigens reported earlier. SV is the most common, and there are strong linkages of SV with Cw2 and Bu with Cw3. The possible presence of further variants at the A- and B-loci is reported. The proportion of B-locus antigen "blanks" in this study is 5.9%. Relationships have been sought between the HLA antigens and diseases studied: the antigen A29, possibly in linkage with Bw42, shows a correlation with disease susceptibility, and associations are suggested between Bw44 (in possible combination with Aw36) and resistance to both BL and NPC, and between Bw45 and long-term remission in NPC.

B15 heterogeneity in East African Blacks.

One-hundred-forty-one Blacks (135 unrelated) from Kenya and Tanzania have been tissue-typed (HLA-A, B and C loci) as part of a study of host factors involved in Burkitt's lymphoma and naso-pharyngeal carcinoma. Evidence is presented for the existence in this population of several B15-related antigens which together occur with a relatively high frequency of 30% in unrelated individuals. It is likely that these variants may include the antigens SV and perhaps Bu recently defined with population frequencies of under 1% in Caucasians. In the absence of monospecific typing sera, identification of these variants may be helped by their apparently strong association with C-locus antigens in Blacks. Recognition of these B15 variants has been largely responsible for reducing the proportion of unidentified or "blank" B-locus antigens in this population to only 6%. These findings substantiate and amplify previous reports suspecting the presence of such antigens in Blacks, and should facilitate studies of possible associations of disease with HLA in these populations.