B cell chronic lymphocytic leukaemia/small lymphocytic lymphoma: role of ZAP70 determination on bone marrow biopsy specimens

Abstract

Background: The course of chronic lymphocytic leukaemia/small lymphocytic lymphoma (CLL/SLL) partly depends on the mutational status of the variable region of immunoglobulin heavy chain genes (IgV H ), which defines two subgroups of tumours: mutated and unmutated. The expression of zeta-associated protein 70 (ZAP70) is significantly associated with the more aggressive unmutated forms. Aims: To assess the feasibility of the ZAP70 immunohistochemical test on bone-marrow biopsy (BMB) specimens and to compare the results with those of western blotting (WB) and IgV H mutational status assessed on neoplastic cells from peripheral blood. Methods: 26 patients with CLL/SLL detected on BMB and with known IgV H mutational status were selected. ZAP70 was determined by immunohistochemistry (IHC) comparing three antibodies from different sources (Upstate, Cell Signaling, Santa Cruz, California, USA) and two different methods (APAAP and EnVision + ). In 23 cases, ZAP70 WB results were also available. Results: ZAP70 determination on BMB specimens turned out to be easily feasible with routine procedures with reagents from Upstate and Cell Signaling. The results were concordant with those obtained with WB and mutational status analysis in .80% of the cases with both reagents. Three of four discordant cases were mutated/ZAP70 positive, with two staining weakly for ZAP70 on both WB and IHC. Conclusions: The study confirms the role of ZAP70 as a possible surrogate of mutational status and emphasises its application in routine diagnostics; it discloses a small subset of discordant cases (mutated/ ZAP70 weakly positive) that clinically cluster with the more favourable forms.

Most Morphologic Features in Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma (CLL/SLL) do not Reliably Predict Underlying FISH Genetics or Immunoglobulin Heavy Chain Variable Region Somatic Mutational Status

“…14,15,18,37 In our study, we found a significant correlation with ZAP-70 positivity and an IGHV unmutated status (11 out of 11 cases, P = 0.001), which seemed to be a specific finding, as none of our IGHV mutated cases were ZAP-70 IHC positive. However, as exemplified by case A (Fig.…”

ZAP‐70 expression is associated with increased risk of autoimmune cytopenias in CLL patients

“…To assess ZAP-70 expression, we utilized immunohistochemical analysis on BM biopsies. The reliability of this technique and the close correlation between ZAP-70 as detected by IHC in BM biopsies and PFS and OS in CLL patients have been previously demonstrated [17,18]. Moreover, this IHC method of evaluation of ZAP-70 using formalin fixed BM biopsies taken at diagnosis allowed the retrospective evaluation of patients with long follow-up.…”

“…Various techniques were used for testing ZAP-70 expression, including flow cytometry and immunohistochemistry (IHC) [13][14][15][16][17]. Although flow cytometry is commonly used, IHC was demonstrated to be a reliable method for this purpose [16][17][18].…”

Vascular endothelial growth factor A (VEGFA) expression in mycosis fungoides

“…Particular attention was paid to the phenotypic characteristics of small‐ to medium‐sized lymphoid elements with highly indented nuclei, regarded as malignant according to the WHO classification criteria . For each marker, as reported previously, the proportion of immunoreactive neoplastic cells was scored as follows: − = zero, exceptional = 1–10%; rare = 11–25%; −/+ = 26–50%; +/− = 51–75%; + = >76% positivity. A similar score was applied to the T cell component of the control cases.…”