Evaluation of CytoDiff™ on cord blood WBC differential

INTRODUCTION

An umbilical cord blood bank was recently opened in our institution as an alternative source of hematopoietic stem cells. Before inclusion of a cord blood in an international register, a WBC with differential is requested, among others. Currently, the reference method is the microscopic manual count, and we sought to evaluate the routine flow cytometric method (CytoDiff™) as an alternative.

METHODS

A total of 161 cord bloods were analyzed between November 2010 and February 2011. WBC differentials were determined for each sample, by (i) the cell counter (DxH800), (ii) a manual review, and (iii) the flow cytometry using the CytoDiff™ antibody cocktail.

RESULTS

Correlation coefficients between flow cytometry and microscopic count were satisfying for neutrophils, lymphocytes, and immature granulocytes and acceptable for eosinophils. On the other hand, we found lower correlation coefficient for basophils and monocytes. Monocytes' correlation was better when comparing flow cytometry with cell counter.

CONCLUSION

The flow cytometric approach is suitable to realize cord blood WBC differential and allows for the identification of additional cell subsets.

Characterization of intratumoral follicular helper T cells in follicular lymphoma: role in the survival of malignant B cells

Accumulating evidences indicate that the cellular and molecular microenvironment of follicular lymphoma (FL) has a key role in both lymphomagenesis and patient outcome. Malignant FL B cells are found admixed to specific stromal and immune cell subsets, in particular CD4(pos) T cells displaying phenotypic features of follicular helper T cells (T(FH)). The goal of our study was to functionally characterize intratumoral CD4(pos) T cells. We showed that CXCR5(hi)ICOS(hi)CD4(pos) T cells sorted from FL biopsies comprise at least two separate cell populations with distinct genetic and functional features: (i) CD25(pos) follicular regulatory T cells (T(FR)), and (ii) CD25(neg) T(FH) displaying a FL-B cell supportive activity without regulatory functions. Furthermore, despite their strong similarities with tonsil-derived T(FH), purified FL-derived T(FH) displayed a specific gene expression profile including an overexpression of several genes potentially involved directly or indirectly in lymphomagenesis, in particular TNF, LTA, IL4 or CD40LG. Interestingly, we further demonstrated that these two last signals efficiently rescued malignant B cells from spontaneous and rituximab-induced apoptosis. Altogether, our study demonstrates that tumor-infiltrating CD4(pos) T cells are more heterogeneous than previously presumed, and underlines for the first time the crucial role of T(FH) in the complex set of cellular interactions within FL microenvironment.