| Abstrakt: |
Decreased hemoglobin concentration occurs at six weeks of age. Its mechanism is unclear. We studied six infants at six weeks of age and their parents, with the in vitro plasma clot assay for erythroid progenitor cells CFU-E and BFU-E. Serum samples and peripheral blood (PB) mononuclear cells (MNC) were obtained by venipuncture. Bone marrow (BM) aspirate MNC were obtained from a normal adult volunteer. MNC were fractionated into T-cells and non-T-cells by sheep erythrocyte rosetting. Some PB-MNC from each baby were pre-incubated with: a) fresh plasma (FP), b) rabbit complement (RC), c) FP and baby's serum (BS) and d) RC and BS, for one hour at 37°C. All cultures contained 5 × 104cells per micro-well. 1 × 104T-cells were added to some experiments. The baby's PB-MNC produced a mean of 7±2 BFU-E colonies per clot, and 9.5±5 BFU-E when cultured in the presence of BS. Pre-incubation with FP, RC, FP+BS and RC+BS produced 5±1, 4±1, 5.5±2 and 4±2 BFU-E respectively. Adding baby's T-cells to his/her parents' PB-MNC increased the number of BFU-E from 11 to 19. BM-MNC produced a control of 250±10 CFU-E and 30±6 BFU-E per clot. In the presence of BS there were 219±30 CFU-E and 26±8 BFU-E. The addition of BS to cultures of baby's PB-MNC or the pre-incubation of these cells with BS and complement showed no significant inhibition of PB-BFU-E. The baby's T-cells increased the number of PB-BFU-E. Similarly, BM-CFU-E and BM-BFU-E were not inhibited by BS. T-cell suppression of erythropoiesis or serum inhibitors of erythropoiesis, either complement mediated or not, do not explain the physiologic anemia of the newborn. |
