Optimal number of reagents required to evaluate hematolymphoid neoplasias: results of an international consensus meeting.

At the ISAC 2000 Congress, the Clinical Cytometry Society organized a meeting of international experts to reach consensus on the minimum number of antibodies required for a full evaluation of hematologic and lymphoid neoplasias. A questionnaire was distributed prior to the meeting to numerous experts from US and European institutions and 13 responses were received. At the meeting, 25 individuals, including most of those who returned responses, participated in the discussions and voted on the issues presented. In chronic lymphoproliferative disorders (CLD), 9 antibodies (anti-CD5, CD19, kappa, lambda, CD3, CD20, CD23, CD10, and CD45) were deemed essential for initial evaluation by 75% of the participants. There was near unanimity that additional markers (selected from CD22, FMC7, CD11c, CD103, CD38, CD25, CD79b and heavy chains for B-cell disorders, and CD4, CD7, CD8, CD2, CD56, CD16, TCRa/b, and TCRg/d for T-cell disorders) would be needed to fully characterize CLD, although not every marker would be useful in all cases. Tissue lymphomas were believed to be similar to CLD, needing a minimum of 12--16 markers. However, for some cases, CD30, bcl-2, TdT, CD71, CD1a, and CD34 were cited as useful by the participants. Markers mentioned for plasma cell disorders included kappa, lambda, CD38, CD45, CD56, CD19, CD20, CD138, and heavy chains. Of 17 voting participants, 16 agreed that between 5 to 8 markers would be essential reagents for plasma cell disorders. For acute leukemia (AL), 10 markers (CD10, CD19, CD13, CD33, CD34, CD45, CD7, CD14, CD3, and HLADR) were considered essential by 75% of participants for initial characterization of the leukemia lineage. Most (>75%) agreed that at least one more B (CD20, CD22, CD79a, IgM), T (CD1a, CD2, CD4, CD5, CD8), myeloid (CD11b, CD15, CD64, CD117, myeloperoxidase), erythroid (CD36, CD71, glycophorin A), and megakaryocytic (CD41, CD61) reagents should be included in the essential panel. However, there was no agreement as to which was optimal. Thus, approximately 13--15 of those reagents would be considered essential in all cases of AL, whereas others (CD16, CD56, CDw65, TdT, and cytoplasmic CD3) were mentioned as useful in some cases. Almost all voting participants believed that the appropriate number of markers for complete characterization of AL would average 20--24. The majority of the responders (11 of 13) indicated that fewer reagents could be used in monitoring or staging patients with previously characterized disease, but not all ventured a specific number of reagents. From the above results, we conclude that the phenotypic analysis of hematologic and lymphoid neoplasia requires a rather extensive panel of reagents. Supplementary reagents might even be necessary if they prove to become relevant for diagnostic purposes. Reducing the number of antibodies could significantly compromise the diagnostic accuracy, appropriate monitoring, or therapy of these disorders.