MEASUREMENT OF RECOMBINASE ACTIVITY IN A SET OF RELATED ABELSON MURINE LEUKEMIC VIRUS PRE-B-CELL LINES - DJ/DJ LINES HAVE MORE RECOMBINASE ACTIVITY THAN DO VDJ/VDJ LINES

The VDJ recombination potential of a number of Abelson murine leukemic virus transformed fetal liver cell lines derived from (C57BL/6 x BALB/c) F1 mice was measured. The specific developmental stage of each line was determined using Southern blot analysis to ascertain their rearrangement status at the immunoglobulin heavy chain locus (DJ/DJ, VDJ/DJ or VDJ/VDJ). It was observed that DNA from DJ/DJ lines gave many more 'subhaploid' bands hybridizing with JH than did DNA from VDJ/VDJ lines. While the lack of appropriate substrate (VDJ/VDJ lines have exhausted the normal IgH substrate) contributes to the decrease in 'subhaploid bands', this result indicates that the rate of ongoing immunoglobulin heavy chain gene rearrangement was higher in the DJ/DJ lines. However, when the lines were examined using the assay developed by Hesse et al. (4) to measure VDJ recombinase activity, it was found that although all lines had recombinase activity, the DJ/DJ lines had four times more VDJ recombinase activity than did the VDJ/VDJ lines.