Excision products of TCR V alpha recombination contain in-frame rearrangements: evidence for continued V(D)J recombination in TCR+ thymocytes.

Cortical thymocytes that express a TCR on their surface continue to express mRNA for the recombination activating genes RAG-1 and RAG-2. As the expression of these genes appears to be necessary and sufficient for V(D)J recombination to occur, this finding suggests that productive TCR gene rearrangement may not by itself terminate TCR recombination. To further study this question, we have utilized a polymerase chain reaction-based strategy to isolate and sequence excision products of secondary TCR alpha gene rearrangement events. Our data shows that TCR alpha excision products from TCR+ thymocytes contain in-frame V-J joints and thus support the concept that V(D)J recombinatorial activity may continue even in thymocytes which have undergone productive TCR gene rearrangement.