Owing to the nearly limitless diversity of immunoglobulin (Ig) variable-region gene rearrangements, such rearrangements represent ideal clonal markers for B-lineage cells. This chapter describes an approach to isolate single cells from frozen tissue sections by microdissection using a hydraulic micromanipulator and the subsequent amplification of rearranged IgH and Igκ genes from the cells in a seminested polymerase chain reaction (PCR) approach. The amplification ofa prioriunknown V-gene rearrangements is made possible by the usage of a collection of V-gene family-specific primers recognizing nearly all V-gene segments together with primer mixes for the J-gene segments. By sequence comparison of V-gene amplificates from distinct cells, the clonal relationship of the B-lineage cells can unequivocally be determined. As a large part of the V-gene rearrangements is amplified, the approach is also useful to address additional issues, such as V-, D-, and J-gene usage and the presence and pattern of somatic mutations.
