Haemoglobin synthesis in human erythroid bursts during ontogeny: reproducibility and sensitivity to culture conditions.

Patterns of haemoglobin (Hb) synthesis were analysed in erythroid bursts grown in vitro from human fetal, umbilical cord and adult blood to determine the reproducibility of the system and its sensitivity to various alterations in culture conditions. The proportion of Hb F synthesis in duplicate plates from the same sample showed little variation but when an individual was studied under the same conditions but at different times, far more variability was observed. We have confirmed that the synthesis of Hb F and Hb A in the cultures is asynchronous, relatively more Hb F being synthesized earlier in the maturation of the colony. Hence factors affecting colony maturation are likely to change the apparent pattern of Hb synthesis. Removal of adherent cells prior to plating resulted in the presence of more mature colonies and lower levels of Hb F synthesis at any fixed time in culture. Furthermore, the overall ratio of gamma:beta chain synthesis measured in the whole plate was dependent on the proportion of large, immature multicluster bursts present. The significance of measurements of Hb synthesis in erythroid bursts can be assessed only if all of these factors are recognized and taken into account.