EXPANSION OF AN UNUSUAL POPULATION OF GR-1(-NODES AND OTHER PERIPHERAL ORGANS OF MICE CARRYING THE LPR GENE()CD3(INT) CELLS IN THE LYMPH)

Granulocytes and extrathymic T cells are often activated simultaneousl y, but they are absolutely separate populations in normal mice. Howeve r, some abnormal extrathymic T cells (i.e., CD3(int) cells) seen in mi ce carrying the lpr gene were found to express a granulocyte marker, G r-1. Such mice include MRL-lpr/lpr mice and SCG mice. In parallel with an age-associated increase of IL-2R beta(low)CD3(int) cells which con tained double-negative CD4(-)8(-) and B220(+)CD2(-) cells, Gr-1(+)CD3( int) cells increased in number in the lymph nodes and other peripheral organs. In addition to a major population of IL-2R beta(low)CD3(int) cells, there is a small population of IL-2R beta(high)CD3(int) cells w hich produce normal Pas mRNA and Pas molecule from the lpr gene. It wa s found that both IL-2R beta(low)CD3(int) and IL-2R beta(high)CD3(int) cell populations contained Gr-1(+) cells. IL-2R beta(high)CD3(int) ce lls tended to contain a higher proportion of Gr-1(+) cells than did IL -2R beta(low)CD3(int) cells. More interestingly, Gr-1(+)CD3(int) cells expressed a considerable level of mRNA of the mG-CSP receptor, simila r to granulocytes. The present study thus yielded further information on an unusual property of abnormally expanding CD3(int) cells in mice carrying the lpr gene. (C) 1997 Academic Press.