GATA-1 measurement in fresh erythroblasts.

The transcription factor was detected in myeloma patients with severe (A-05) or without (B-08) anemia showing a discrepancy in their extent of GpA^+dim (R1) and GpA^+bright (R2) populations. The immature erythroblast subset expressing GATA-1 at very low intensity (M1) was considerably expanded in the anemic patient (76.1% versus 37.3% of patient B-08) to the detriment of the M2 population, which included immature erythropoietic cells with a regular to high content of GATA-1. Conversely, the M2 population was substantial (62.4%) in patient B-08. GATA-1 at either low or high fluorescence intensity was similarly expressed as percentage of positive cells in both patients, though the proportion of the mature erythroblast population was modest in the anemic patient.