Following the Life History of Lymphocytes 
Peyer's patches as well as to bind to the blood 
vessels in the traffic zones of Peyer's patches, 
whether the a^fi-j molecules were found to be ex- 
pressed on these lymphomas or were transfected 
to them by our cDNA clones. Antibodies to either 
or jSy could block this selective adhesive event. 
We have also developed a new mouse strain by 
transgenic technology, deleting all cells that ex- 
press the activated killer cell gene granzyme A 
(first identified and cloned in this laboratory) by 
attaching to that gene a "suicide" gene obtained 
from Richard Palmiter (HHMI, University of 
Washington). When killer cells are activated in 
this mouse strain they begin to express the diph- 
theria toxin A chain suicide protein, and die. Un- 
expectedly, we have uncovered in this transgenic 
mouse strain a profound effect on the life span of 
all CDS T cells, and not just killer T cells and 
natural killer cells. In the next year, we plan to 
utilize these mice to delineate the role of killer 
cells in normal and pathological immune reac- 
tions in vivo and to define the mechanism by 
which non-killer CDS T cells are deleted after 
their emigration from the thymus. 
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