CD34+ cell content predicts the haematopoietic potential of a CB unit better than nucleated cell content. Accordingly, the CD34+ cell content of CB could be used to select CB for banking purposes and for transplantation.

No abstract

We describe immunization of two mothers against a new platelet alloantigen, designated Tua, in association with thrombocytopenia in their first born children. The platelet-specific antibodies were identified by a glycoprotein-specific platelet protein assay with husband's platelets. Monoclonal antibodies against glycoprotein complex IIb/IIIa (AP2) and against glycoprotein IIb (SZ22) could be used to immobilize the antigen bearing protein. When monoclonal antibodies against glycoprotein Ib/IX (FMC25) or Ia/IIa (Gi9) were used, no platelet-specific antibodies were detectable. The previously described alloantigens on the glycoprotein IIb/IIIa complex (HPA 1,3,4, Sra and Vaa) were not responsible for the reaction. Immunochemical analysis by an immunoblot assay showed that the Tua antigen resides on GPIIIa but the antigen was destroyed by reduction of the protein. Altogether 10 individuals belonging to three unrelated families were shown to carry the antigen. The family studies within three generations indicated autosomal codominant inheritance. Thus the Tua antigen is apparently different from all previously published platelet alloantigens. One Tua positive blood donor was identified in a population study of approximately 150 individuals. This indicates a low frequency in the Finnish population. Extended population studies will be required to determine a more exact frequency of Tua antigen.

Aim: CD34+ cell counts are used to define the haematopoietic stem cell potential of a given cord blood transplant. The aim was to test the hypothesis that high concentration of cord blood haematopoietic progenitor and stem cells could be a reflection of intrauterine growth, of which birthweight is an indicator. Methods: Simple and multiple regression analyses were applied to test cord blood bank data on 1368 infants for associations of selected obstetric factors and cellular contents of cord blood. Results: When groups were formed based on the extreme values (5th versus 95th percentiles) of a given variable, e.g. birthweight, the term infants having the highest birthweights were found to have statistically significantly higher median cord blood CD34+ cell concentrations. Also, infants in the top 50th percentile of relative birthweight had higher median CD34+ cell concentration than infants in the low 50th percentile. In multiple regression analysis, the correlation between birthweight and CD34+ cell concentration was statistically clearly significant. Notably, while an expected correlation between gestational age and nucleated cell concentration was found, there was no association between infant gestational age and CD34+ cell concentration. Conclusion: Haematopoietic progenitor and stem cells may reflect intrauterine growth and have a more central role in foetal development than has been reported earlier.

A simple PCR-based protocol for HLA-DR typing suitable for a routine practice is described. The method involves, first, a PCR amplification with seven different, group-specific (DR1, DR2, DR4, DR7, DR9, DR10, and DR3+5+6+8) primer-pairs, and second, typing of HLA-DR allele more exactly in DR1, DR2, DR4, and DR3+5+6+8 groups by digestion of PCR products with restriction enzymes distinguishing different HLA-DR types within each of the groups. Altogether 24 HLA-DR alleles, or any combination of these, can be typed. The whole procedure, starting from a blood sample, can be carried out during a single working-day. The method was tested by typing a set of homozygous cell lines, as well as a local panel previously typed by PCR/oligotyping. Also, 227 patients waiting for transplantation were typed to test the method in a routine setting. The results suggest that this kind of approach gives reliable HLA-DR types and works well in the routine use.