Sue Armitage

CD34 counts to predict the adequate collection of peripheral blood progenitor cells

An essential prerequisite for successful procurement of sufficient autologous peripheral blood progenitor cells (PBPC) for engraftment is the optimal timing of collection. A number of surrogate markers of peripheral blood progenitor cells were analysed to identify a single test which could predict the optimum time to harvest, providing at least 2 × 106 CD34+ cells/kg patient body weight. The study comprised 95 patients undergoing varied mobilisation regimens with chemotherapy and G-CSF for both solid tumours and haematological malignancies. One hundred and fifty-seven PBPC harvests were collected. Full blood counts (FBC) and CD34+ cell enumeration was performed on blood samples taken during the mobilisation period and immediately prior to leucapheresis (pre-harvest). All PBPC collections were assayed for colony-forming cells and CD34+ cells in addition to a FBC. The white cell count on the day of harvest showed only weak correlation with the total number of CD34+ cells in the collection (r = 0.30). In contrast, the absolute number of circulating CD34+ cells strongly correlated with the CD34+ cell and CFU-GM yield of the corresponding apheresis product. Provided the mobilisation sample contained ⩾20 × 106 CD34+ cells/ml, 94% of single collections, performed the following day, contained ⩾2 × 106 CD34+ cells/kg.

Cord blood banking in London : the first 1000 collections

The London Cord Blood Bank was established with the aim of collecting, processing and storing 10000 unrelated stem cell donations for the significant number of children in the UK requiring transplantation, for whom a matched unrelated bone marrow donor cannot be found. Collection is performed at two hospitals by dedicated cord blood bank staff after delivery of the placenta. Mothers are interviewed regarding medical, ethnic and behavioural history by nurse counsellors and sign a detailed consent form. Donations are returned to the bank for processing. Volume reduction is undertaken by a simple, closed, semi-automated blood processing system, with excellent recovery of progenitor cells. Units are cryopreserved and stored in the vapour phase of liquid nitrogen. Blood samples from mothers and cord blood donations are tested for the UK mandatory red cell and microbiology markers for blood donors. Donations are typed for HLA-A, B and DR at medium resolution (antigen split) level using sequence-specific oligonucleotide probing and sequence-specific priming techniques. The selection of collection hospitals on the basis of ethnic mix has proven effective, with 41.5% of donations derived from non-European caucasoid donors. Bacterial contamination of collections has been dramatically reduced by implementation of improved umbilical cord decontamination protocols.

The London Cord Blood Bank: analysis of banking and transplantation outcome

Cord blood units (n = 5500) stored at the London Cord Blood Bank, including 59 units transplanted into a high risk and heterogeneous group of patients, were analysed. Transplant outcome data was available for 44 patients with a median clinical follow‐up of 14 months (range 3–44 months). Over 40% of the collected units were of ethnic minority origin with a median volume of 79 ml (range 40–240 ml) and a median total nucleated cell (TNC) count of 11·9 × 109/l (range 10·0–24·8 × 109/l). The average patients weight was 28 kg (range 5–80 kg) and the median age was 8 years (range 0·7–40 years). The median number of nucleated cells infused was 4 × 107/kg (range 1·10–16 × 107/kg). Neutrophil engraftment of 0·5 × 109/l was observed in 33 (74±%) patients with an average time of 28 days (range 11–60). The Kaplan‐Meier estimate of acute graft‐versus‐host disease (grade II >) at day 100 was 37 ± 7% and in 27 (62%) patients, it was grade I or absent. The overall survival and disease‐free survival at 2 years was 49 ± 8% and 41 ± 8%, respectively. Two years after transplantation the survival rate was 69% and 54% for patients receiving a 6/6 or 5/6 HLA matched units, respectively. Infection was the main cause of transplanted related mortality in these patients.

Cord blood banking: volume reduction of cord blood units using a semi-automated closed system.

Clinical evidence indicates that placental/umbilical cord blood (CB) is an alternative source of haematopoietic stem cells for bone marrow reconstitution. To establish a CB bank large panels of frozen, HLA-typed CB units need to be stored. Cryopreserved, unprocessed CB units require vast storage space. This study describes a method, using the Optipress II Automated Blood Component Extractor (Opti II) from Baxter Healthcare Corporation, to reduce the volume of the CB collection, preserving the quantity and quality of the progenitor cells, in a closed system. The CB collection was transferred to a triple bag system, centrifuged to produce a buffy coat layer and processed using a standard Opti II protocol to separate the whole blood into three components: plasma, buffy coat and buffy coat-depleted red cell concentrate. The buffy coat volume was standardised to 25 ml; mean reduced volume of 24.5 ml (s.d. 1.5 ml) with 53% red cell depletion. Good recovery of cells was observed: 92%, 98%, 96% and 106% recovery of nucleated, mononuclear, CD34+ and total colony- forming cells, respectively. Using this method for processing CB units reduces storage requirement by two-thirds but preserves the quantity and quality of the progenitor cells.

An international survey of unrelated umbilical cord blood banking

To investigate operational and technical practices within the field of cord blood banking.

Response to immunization with A and B human glycoproteins for the procurement of blood grouping reagents

Abstract. 37 subjects have been immunized with A or B human blood group substances. All subjects showed at least a threefold increase in potency of their ABO antibodies. Use of the resulting plasma has considerably improved the quality of our ABO grouping reagents. The IgG component of these antibodies increased in all subjects and an IgA component was seen in the majority of post‐immunization samples. All group O subjects developed cross‐reacting anti‐A,B antibodies.

Development of ‘auto-anti-A1 antibodies’ following alloimmunization in an A2 recipient

In the majority of cases Al antibodies fail to react at 3 7°C and are of no clinical significance. Haemolytic transfusion reactions due to A1 antibodies active at 37OC are extremely rare (see Mollison, 1983). In most cases the immunoglobulin class of the antibody has been shown to be IgM. Only one case of a delayed haemolytic transfusion reaction due to IgM and IgG anti-A1 in an A2B patient has been reported by Lundberg & McGinniss (1975). Cold reacting auto anti-A or anti-Al IgM, usually of no clinical significance, have been found occasionally. However, only two well-documented cases of autoimmune haemolytic anaemia due to anti-A autoantibodies have been published (Szymanski et al, 1976; Parker et al, 19 78). In the first case the autoantibody is likely to have been IgG or a mixture of IgM and IgG whilst in the latter case it was probably pure IgM. We here report a severe delayed haemolytic transfusion reaction in an A2 patient who was transplanted with a kidney from a group 0 donor and at about the same time was transfused with 3 units of A1 blood. Anti-A1 developed about 1 week after and at this time the direct antiglobulin test (DAGT) became positive and remained so long after the transfused A1 red cells had been eliminated.

Serology and genetics of an MNSs-associated antigen Dantu.

Dantu, a previously undescribed low‐incidence red cell antigen, is inherited as a Mendelian dominant character. The Dantu antigen is associated with very weak s antigen, protease resistant N antigen and either very weak or no U antigen. Two of the propositi had previously been shown to have an unusual hybrid MNSs sialoglycoprotein, and it is probably this which carries these unusual N, s and U antigens as well as the Dantu antigen. A study of the family of one propositus suggests, by conventional genetics, that Dantu is not controlled by the MNSs locus; a possible explanation is given. Several examples of anti‐Dantu are known, one was found to cause a positive direct antiglobulin reaction on neonatal red cells.

The MNSs Antigen Ridley (Ria)

After more than 20 years the extended pedigree of the only known kindred carrying the low frequency antigen Ria (Ridley) was reinvestigated. It is established that Ria is governed by a gene which is part of or very closely linked to the MNSs locus. Further serological and frequency studies are reported.

The Incidence of Antibodies to Low Frequency Antigens (LFA) in Plasmapheresis Donors with Hyperimmune Rh Antisera

Summary. Over 50% of plasmas from plasmapheresis donors hyperimmunized for Rh antibodies were found to contain antibodies to low frequency red cell antigens (LFA). The majority of these plasmas contained antibodies to more than one LFA. On the other hand, the incidence of these antibodies in immune plasma from control plasmapheresis donors was markedly lower. The significance of the high incidence of these antibodies in grouping reagents is discussed.