Tcells isinversely related to thedeclining T-cell activities inaging mice

ABSTRACT The frequency of clonable 6-thioguanine-resistant(6-TGr)splenic Tcells increased moderately with agein female BALB/cmiceranging in agefrom 3 to 32 months;however, the correlation between the frequency of clonable 6-TGr cells and age was weak. Those clonable 6-TGr Tcells weredeficient in hypoxanthine/guanine phosphoribosyltrans- ferase (HGPRT) activity and sensitive to hypoxanthine/ aminopterin/thymidine medium, as in the case of HGPRT-deficientL5178Ymouselymphomacells. When splenic Tcellsofindividual aging micewereassessed simultaneously for the frequency of clonable 6-TGr T cells and for their ability toproduceinterleukin 2 orto proliferate in response to mitogenicstimulation, an inverse correlation wasobserved. Theseresults indicate thatthe frequency of6-TGrTcellsismore closely relatedto physiologicage than chronologicage. Thiswouldmeanthatthe frequencycouldbeusedas anindexofphysiologic ageandthat theTcellscouldserveasacellularmodel relatinggenealterationsto physiologic age.