[Semiquantitative monitoring of molecular markers in non-Hodgkin's lymphoma].

BACKGROUND: As quantitative changes of disease specific molecular markers may reflect disease activity, various methods quantifying targets of polymerase chain reaction were developed and their clinical relevance should be established. METHODS AND RESULTS: Here the exploitation of the DNA limiting dilution methodology in molecular monitoring of non-Hodgkin's lymphomas is presented. Long-term stored diagnostic DNAs are checked for their integrity and examined in dose-response assays for semiquantitative estimates of t(14,18) translocations and clonal immunoglobulin heavy-chain gene rearrangement. Assuming that the specific targets are diluted proportionally by dilution of total genomic DNA, sensitivities of polymerase chain reaction expressed as minimal amounts of total cells in reaction initiating positivity are compared. The term PCR-detectability as the ratio of sensitivities determined for preceding and actual samples is introduced. The value of PCR-detectability lower than one is considered as an indicator of a decrease of cells bearing the marker and vice versa. So far, the considerable increases in PCR-detectabilities were found close to relapses and unsubstantial changes at clinical remissions. CONCLUSIONS: It is presumable, that the semiquantitative limiting dilution approach may contribute to the monitoring of disease and treatment outcome.