The outcome of pregnancy in Kell alloimmunisation.

OBJECTIVE: To assess management and outcome of pregnancies with anti-Kell in the West Midlands in the UK over 13 years. DESIGN: A retrospective review of casenotes. SETTING: A regional referral clinic for red cell alloimmune disease and fetal medicine unit at a university hospital. POPULATION: Sixty-five pregnancies were identified in 52 Kell-sensitised women with Kell positive partners from the records of the Birmingham Blood Transfusion Centre. METHODS: Information from the casenotes was entered on a database and comparisons were made using the SPSS for Windows statistics package. MAIN OUTCOME MEASURES: Mode of sensitisation, degree of fetal or neonatal anaemia, need for transfusion, gestation at delivery, birthweight and pregnancy outcome. RESULTS: Alloimmunisation was transfusion-related in 29 pregnancies and pregnancy-induced in 33. The cause could not be identified in three cases. There were 22 proven Kell positive fetuses, of which 18 were affected, in which alloimmunisation was pregnancy-related in 12 cases and transfusion-related in five. Antibody titres and amniotic fluid OD450 were not helpful in management. Severe or very severe disease occurred in 50% of the affected pregnancies (9/18). There was no difference in pregnancy outcome between transfusion or pregnancy induced sensitisation. CONCLUSIONS: Anti-Kell alloimmunisation is an uncommon cause of serious anaemia in a significant proportion of affected pregnancies. There appears to be no difference between that caused by pregnancy or transfusion. Estimation of fetal haemoglobin concentration by cordocentesis is recommended, as antibody titres and amniocentesis are not helpful.

Importance of a quality assurance scheme for factor VIII assays in quality monitoring of human plasma destined for fractionation into factor VIII concentrate.

A national quality assurance scheme has been established to monitor the validity of factor VIII assays performed by the various laboratories of the Scottish National Blood Transfusion Service engaged in collection and processing of donor plasma destined for fractionation. The results over the first 3-year period show that comparable assay values can be obtained by participating centres using a common standard, despite differences in equipment, methods or substrate chosen for the one-stage assay. The results also showed that chromogenic factor VIII assays correlated well with the one-stage method. Random factor VIII assays performed on plasma, harvested and frozen within 18 h from collection, were analysed to validate recently proposed Scottish specifications which stipulate that 70% of plasma donations destined for fractionation should contain at least 0.7 IU/ml. Plasma harvested and frozen between 8 and 18 h from collection did not meet the specified level in any of the regional centres. This nationally specified level was also not met by plasma harvested and frozen within 8 h from collection in spite of being achieved individually by three regional centres. Assays performed on large plasma pools at the Fractionation Centre suggested loss of some factor VIII during storage, transportation and thawing of plasma prior to bulk processing.

LKE red cell antigen and its relationship to P1 and Pk: serological study of a large family.

The fourth example of human anti-LKE was identified in the serum of an antenatal patient. Study of the red cells of the proband and her family confirmed the recessive inheritance of the LKE- phenotype. The blood groups of the family confirmed that Pk expression is greater on cells from LKE- members than on those from LKE+ members. In this family, the expression of LKE varied with the P1 phenotype. LKE- individuals occurred with an incidence of 0.0017 in the donor population of the Glasgow and West of Scotland Region.

Passive haemagglutination inhibition for quantitation of red cell associated IgG.

Passive haemagglutination inhibition (PHI) was adapted to quantitate red cell associated IgG. Twenty one patients with autoimmune haemolytic anaemia (AIHA) had a raised red cell associated IgG, mean (SD) = 5.783 (6.183) ng/10(6) red blood cell compared with that of 69 subjects with a red cell associated IgG of 0.433 (0.349) ng/10(6) red blood cell. Thirteen of 14 blood donors with a positive direct antiglobulin test (DAGT) had a normal red cell associated IgG. The only blood donor with positive DAGT and raised red cell associated IgG had AIHA. Studies of red cell associated IgG in other groups of patients were also undertaken. The technique is simple, does not require the use of sophisticated equipment, and is suitable as a routine test in hospital laboratories. The results of red cell associated IgG by PHI are reproducible and clinically relevant.

Anti-Rh 29 in a primigravida with rhesus null syndrome resulting in haemolytic disease of the newborn.

This is the first British patient to be reported with the rhesus null phenotype. Anti-Rh 29 was detected in a primigravida at 35 weeks' gestation and rose substantially before delivery. She had all the features of the rhesus null syndrome and her newborn was affected by haemolytic disease (HDN).

Intravenous immunoglobulin therapy for idiopathic thrombocytopenic purpura.

Twenty-two patients with idiopathic thrombocytopenic purpura were treated with high-dose intravenous immunoglobulin infusions using an intact intravenous immunoglobulin preparation and a product designed for intramuscular administration. Seventeen patients (77%) responded favourably (rise in platelet count to 100 X 10(9)/1 or above). Children responded better than the adults, and the acute cases better than the chronic. Splenectomy and the presence of detectable platelet antibody had no effect on the response rate. Both products induced identical responses.

Frozen recovered red cell boosting of female donors for anti-D-production.

A selected group of women previously immunized in pregnancy by the Rh(D) antigen were boosted with 0.5 ml of Rh(D)-positive frozen recovered red cells from an accredited donor panel. The response was prompt and sustained and increased the anti-D content by almost 10-fold. In spite of the reduced rate of clinical immunisation to the Rh(D) antigen, it was possible to recruit females with anti-D, acquired in pregnancy, for secondary boosting and a programme is recommended which maximizes efficiency and safety.

Successes and failures of intravenous immunoglobulin.

11 patients suffering from primary and secondary severe haematological disorders of possible immune origin were treated with high-dose intravenous immunoglobulin. The responses obtained were partial in 3 and negligible in 8.

Measurement of factor VIIIRAg-1. A method for use in the Hyland laser nephelometer.

Factor VIIIRAg was measured by laser nephelometry using a new diluent containing a citrate-carbonate buffer, pluronic polyol P94 and triton X100. No pre-treatment of the samples was required, the incubation time was 0.5 to 1.5 hours depending on the antiserum used, and the tests could be read during the following 4 hours (plasma) or 1.5 hours (intermediate purity F VIII). The CV for the assay was less than 10% for plasma or dilutions of plasma in which the minimum detectable amount of factor VIIIRAg was about 0.04 u/ml. A significant correlation was obtained between the nephelometric method and the Laurell rocket method using plasma, but agreement between the methods when therapeutic products were assayed was poor.