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.