THE DIVERSITY OF IN-FRAME TCR DELTA-CHAIN TRANSCRIPTS IN AGING SCID MICE

From spleen, liver, bone marrow, and gut of old C.B-17 scid/scid (SCID ) mice, TCR delta chain transcripts were amplified by the polymerase c hain reaction (PCR) using V(delta)1-, V(delta)2-, V(delta)3-, V(delta) 4-, V(delta)5-, V(delta)6-, and C(delta)-specific primers. Selectively amplified, TCR delta-chain-encoding cDNA from these organs of five ol d SCID mice was cloned, and 175 randomly selected clones were sequence d. In this panel, 44 distinct rearrangement events were detected, 82% (36/44) of which were in-frame. For V(delta)2, V(delta)4, V(delta)5, a nd V(delta)6, 34 in-frame transcripts were found in five old SCID mice . No potentially functional transcript containing V(delta)3 was found and an unusual type of transcript containing the V(delta)1 gene segmen t spliced directly in-frame to C(delta) was the predominant type of V( delta)1 expression. Junctional diversity was evident in most sequenced clones indicating an extensive potential diversity of SCID-derived TC R delta chains. Identical transcripts were amplified from different or gans of the same old SCID mouse. No organ-specific expression of V(del ta) genes was evident. TCR delta chain transcripts could be neither am plified from young SCID mice nor from young SCID mice nor from young o r old scid/scid nu/nu mice (bred on a BALB/c background). Hence, an ap parently thymus-dependent development of oligoclonal populations of TC Rdelta+ cells is observed in old SCID mice.