Expansion of an Unusual Population of Gr-1+CD3intCells in the Lymph Nodes and Other Peripheral Organs of Mice Carrying thelprGene

Granulocytes and extrathymic T cells are often activated simultaneously, but they are absolutely separate populations in normal mice. However, some abnormal extrathymic T cells (i.e., CD3intcells) seen in mice carrying thelprgene were found to express a granulocyte marker, Gr-1. Such mice include MRL-lpr/lprmice and SCG mice. In parallel with an age-associated increase of IL-2RβlowCD3intcells which contained double-negative CD4−8−and B220+CD2−cells, Gr-1+CD3intcells increased in number in the lymph nodes and other peripheral organs. In addition to a major population of IL-2RβlowCD3intcells, there is a small population of IL-2RβhighCD3intcells which produce normal Fas mRNA and Fas molecule from thelprgene. It was found that both IL-2RβlowCD3intand IL-2RβhighCD3intcell populations contained Gr-1+cells. IL-2RβhighCD3intcells tended to contain a higher proportion of Gr-1+cells than did IL-2RβlowCD3intcells. More interestingly, Gr-1+CD3intcells expressed a considerable level of mRNA of the mG-CSF receptor, similar to granulocytes. The present study thus yielded further information on an unusual property of abnormally expanding CD3intcells in mice carrying thelprgene.