Recombinant-based competitive anti-HIV assay: solution of some operating problems.

Using the Wellcozyme anti-HIV recombinant assay at 47 degrees, a strongly reactive result with an anti-HIV positive serum sample could not be reproduced when the corresponding plasma sample was used. Dilution in anti-HIV negative serum or kaolin treatment of the plasma specimen produced the clear reactivity seen with the serum sample, and a reduction in incubator temperature was also found to reduce this 'plasma effect'. Problems were also encountered initially when haemolysed serum or plasma with non-standard concentrations of anticoagulant were tested.

Use of a bacterial sampler for rapid transfer of microvolumes into microplates.

A method has been devised to transfer very small volumes of serum from microplates prepared during routine screening of blood into microplates containing diluent. Simultaneous transfer of 96 samples is achieved without the need for disposable tips, while still avoiding carry-over between different plates. Using this method a mean transfer volume of 0.

Comparison of IgM and IgG anti-A and anti-B levels in Asian, Caucasian and Negro donors in the North West Thames Region.

This study was undertaken to test the widely held belief that higher levels of immune anti-A and anti-B are characteristic of Negro and Asian populations with a corresponding increased risk factor for AB0 haemolytic disease of the newborn. Overall, 300 serum samples from male and female Asian. Caucasian and Negro blood donors in the North West Thames Region of groups A, B and 0 were collected.

Screening plasma donors for high-titre antibody to cytomegalovirus using a latex agglutination test.

Cytomegalovirus (CMV) can cause severe morbidity in immunosuppressed patients. Regional transfusion centres in the UK are required to supply high-titre anti-CMV plasma to the Blood Products Laboratory (BPL), now called 'Bio-Products Laboratory', for the production of specific intravenous immunoglobulin at the Protein Fractionation Centre in Scotland. For this purpose, 703 plasmapheresis donors were screened by a modified latex agglutination test to assess their suitability as donors with high-titre anti-CMV.

Should anti-Rh immunoglobulin be given D variant women?

D variant women occasionally form anti-D during or following pregnancy with a D-positive fetus. It is not known whether Rh immunization could be suppressed by using anti-Rh immunoglobulin (Rh Ig), or whether the injected antibodies would be absorbed by the woman's D variant cells. In order to predict the likely outcome, three anti-Rh Ig preparations were absorbed independently with five examples of D variant red cells: R1VIr (n = 3), R1Br (n = 2), and with cells of common Rh-positive and Rh-negative phenotypes: R0, r'r, r"r or rr cells (n = 1 each).

Maternal alloimmunization to HLA, platelet and granulocyte-specific antigens during pregnancy: its influence on cord blood granulocyte and platelet counts.

In order to obtain an estimate of the frequency of platelet-specific and granulocyte-specific antibodies and of the effect of such antibodies on the platelet count and granulocyte count of the newborn infant, serum from 147 women in their second or subsequent pregnancies was tested. No platelet-specific antibodies were found but 29 of the women had granulocyte-specific antibodies and the corresponding infants had granulocyte counts which were significantly lower than those of infants without antibodies. HLA antibodies were found in the sera of 57 women but were not associated with diminished platelet or granulocyte counts in the corresponding infants.

Provision of a panel of anti-toxoplasma-negative blood donors.

Toxoplasma gondii has been reported to cause complications only in immunosuppressed patients receiving leucocyte transfusion, when severe acute toxoplasmosis has been reported with associated mortality. At the North London Blood Transfusion Centre (NLBTC) we have screened 392 plasmapheresis donors (using toxoreagent latex agglutination test manufactured by Eiken) to provide a panel of blood donors negative for antibody to toxoplasma for seronegative recipients. A toxoplasma-negative panel of donors would only be required for those rare instances when granulocyte concentrates are indicated for transfusion of seronegative recipients.

The Rh-negative donor.

By typing fully for Rh, donor samples found to be D-negative but C-positive and/or E-positive on the Kontron Groupamatic G2000, the incidence of Ccddee (r'r) was found to be 0.44%, ccddEe (r"r) 0.50% and Du 0.

Analysis of the heterogeneity of the binding site specificities of hyperimmune human anti-A and -A, B sera: the application of competition assays using murine monoclonal antibodies.

Monoclonal antibodies PL41 and AL62 have previously been shown to recognize two distinct blood group A epitopes on the red cell surface. Competitive inhibition of the binding of 125I-PL41 and 125I-AL62 to group A1 red cells, by hyperimmune polyclonal human antibodies, has been employed to investigate the binding site specificities of 15 anti-A and 8 anti-A,B sera. Differences in the degree of inhibition of the binding of the two MABs by individual anti-A or -A,B samples indicate that polyclonal reagents are composed of varying proportions of up to 3 (or more) different antibody specificities, each recognizing a distinct epitope: PL41-like, AL62-like and a third (as yet undefined) category of antibody.

Noncellular immunoadsorbents for preparing typing sera that recognize high-frequency red cell antigens.

The feasibility of using salivary ABH substance, covalently coupled to an affinity gel as an immunoadsorbent for anti-A and -B in sera containing antibodies to high-frequency antigens was investigated. Several examples of anti-Hy (n = 4), -Jra (n = 3), -U (n = 3), -Lub (n = 3), -Tja (n = 8), and -Vel (n = 6), plus one anti-Coa, were treated by batch adsorption with the affinity gel. Titration of the adsorbed sera with ABO-incompatible cells lacking the relevant high-frequency antigen, in parallel with ABO-compatible cells expressing the high-frequency antigen, revealed that ABO antibodies could be adsorbed to exhaustion without loss of the sera's activity against cells bearing high-frequency antigens.

A prospective study of the incidence of delayed haemolytic transfusion reactions following peri-operative blood transfusion.

Delayed haemolytic transfusion reactions (DHTRs) are a recognized sequel of blood transfusion. The true incidence and importance of this complication have been difficult to estimate due to the lack of any prospective studies. We have carried out such a study by testing 530 patients who were transfused during cardiac surgery.

Induction of red blood cell destruction by graft-derived antibodies after minor ABO-mismatched heart and lung transplantation.

Heart-lung transplantation (HLT) unlike other solid-organ transplants involves transplantation of a large amount of lymphoid tissue; hence there is considerable potential for graft-versus-host reaction if there is an antigen mismatch between donor and recipient. Due to the shortage of suitable donors, minor ABO-mismatched HLT (group O organs given to A, B, or AB recipients) are performed. Of 84 consecutive HLT at Harefield Hospital, nine fully ABO-matched and nine ABO-mismatched HLT were studied.