More on CD10-positive cells in the bone marrow of children with immune thrombocytopenia.

Acknowledgments: Received xxx; acceptedxxx Sir, we read with interest the paper by Melillo et al. dealing with increased CD10 cell: in the bone marrow (BM)of a child with immune thrombocytopenia (ITP). In this context we would lime to report our experience based on the bone marrow immunological analysis, carried out at the time of diagnosis, in 13 ITP children observed at our institution in the last year. Results were compared with those of 13 ITP adult patients intentionally selected for statistical comparison. Diagnosis of ITP was made in all instances according to well established criteria. Other immune disorders were excluded on the basis of Coombs. test and ANA negativity. A panel of monoclonal antibodies which included CD10, CD34, CD19, HLA-DR, CD20, CD38, CD3, CD4, CD8, CD5, CD23 was used for BM immunophenotyping. All BM samples were taken at diagnosis and more than 5u10/L cells were analyzed in flow cytometry. Result of BM immunophenotype are depicted in Table 1. As shown, adult patients had an increased percentage of T-cells in BM in comparison to younger ones. In contrast, children with ITP displayed a significant increase of Bcell lineage antigens. The same applied for both CD10 and CD34. The FACS profile from a representative patient stained for CD10 is presented in Figure 1B. As shown, the histogram suggest the presence of a CD10 cell population with weak fluorescence. On the other hand, mean fluorescence intensity (MFI) in our ITY cases was significantly lower (86.5±10.9) than that encountered in CD10 ALL patients (119±12.6)(Figure 1a). In order to verify whether CD10-expression was an age-related phenomenon rather than a feature of ITP we attempted a correlation with patient age. Results are consistent with a negative correlation between CD10-positivity and patient-age (r=–0.709; p<0.01). In other words, the higher CD10-expression the lower patientage. Previous study from Cornelius et al. stressed that ITP children may have an increased number of BM CD10 cells than normals. However, MORE ON CD10-POSITIVE CELLS IN BONE MARROW OF CHILDREN WITH IMMUNE THROMBOCYTOPENIA