Chimeric drift in blood cell populations of chimeric rats constructed between congenic strains.

Chimeric drift is the shift in the proportion over time of the two cell lineages which comprise a chimera (genetic mosaic). Chimeric drift in blood cell populations is determined by both the probability of proliferation from stem cell pools of one or the other of the cell lineages which constitute the chimera and the effects of life span in circulating blood cells. Previous evidence suggests that while chimeric drift occurs in chimeras between genetically disparate strains, it does not occur when the strains used are closely related. No information is available from chimeras between congenic strains. In the present study, chimeric rats were produced between strains with distinguishable class I major histocompatibility complex haplotypes, PVG-RT1a and PVG (which express the haplotype RT1c). PVG-RT1a-specific monoclonal antibodies were used to establish the mosaic patterns in the cell populations of peripheral blood by fluorescein-activated cell sorting. Mosaic cell lineage of red blood cells, white blood cells, lymphocytes, monocytes and neutrophil populations were analyzed weekly over a period of 6 weeks. The ratio of cells of the PVG-RT1a lineage to cells of the PVG lineage shifted either in favor of PVG-RT1a or PVG in cellular components of peripheral blood. The percentage of PVG-RT1a cells in peripheral blood of chimeras changes by as much as 54, 28, 21, 19 and 23% in red blood cell, white blood cell, lymphocyte, monocyte and neutrophil populations, respectively. The shifts in the percentage of PVG-RT1a cells appears to occur in a cyclic fashion.(ABSTRACT TRUNCATED AT 250 WORDS)