Frozen sections of cellular lymphoid proliferations provide adequate DNA for routine gene rearrangement analysis

Optimal use of frozen tissue procured as part of a thorough diagnostic workup of suspected lymphoma is important, and conservation of similar samples is a prerequisite for maintaining a large and varied frozen archive repository. The authors have evaluated a simple tissue-conserving method for the preparation of cellular lymphoid specimens for immunoglobulin and T-cell receptor gene rearrangement analysis. Initially, 16-microns-thick frozen tonsil sections were examined to determine adequacy for DNA extraction. Specimens containing three, six, and nine sections each were evaluated separately. DNA quantitation disclosed yields ranging from 84 to 204 micrograms (mean, 156 micrograms). The authors have used this technique on 24 cellular lymphoid proliferations from their frozen archives. Six to ten 16-microns sections were used, depending on tissue size. DNA quantitation ranged from 0 to 520 micrograms (mean, 135 micrograms). Twenty-one of 24 cases yielded adequate DNA for analysis; each showed appropriate germline or rear-ranged bands with respect to the particular morphologic diagnosis. Attempts to obtain adequate DNA with the use of this technique on skin biopsy specimens with lymphoid infiltrates resulted in overall poor yields; this may be because of dermal collagen or small sample size. This method of sample preparation provides adequate DNA for routine Southern blot hybridization analysis of cellular lymphoid tissues and offers the additional advantage of allowing preservation of frozen tissue for future study.