Prognostic role of natural killer cells in pediatric non-Hodgkin's lymphomas

Abstract

The study of background cells in tumors as a prognostic parameter has been a great concern in pathology. Natural killer cells have spontaneous cytotoxic capacity against tumor cells. Their prognostic significance in non-Hodgkin's lymphoma has yet to be determined. Fifty-seven pediatric non-Hodgkin's lymphoma patients (containing noncleaved cell, lymphoblastic and large cell subtypes) are included in this study. Immunohistochemical stains were performed for natural killer cells using a monoclonal antibody CD57 in sections of appropriate paraffin blocks. CD57 positive cells among 5000 cells were counted on immersion objective. The degree of natural killer cells was classified as low (<125 cells) and high ($\geq$125 cells). Multivariate regression analysis was performed to determine the differences between alive patients with and without relapse. The mean of CD57 positive cell number is 149±130 (10- 500). CD57 positive cells were high in 29 cases (51%) and low in 28 (49%) cases. The mean of CD57 positive cell number is 170±140 in disease free group, and 76±39 in relapsing or exitus group. Correlation analysis and chisquare tests showed relationship between CD57 high and low expression and prognosis, stage and diagnosis. In multivariate analysis, CD57 expression proved to be a prognostic factor independent from other factors. But log rank analysis did not show statistical significance between event free survival and CD57 expression intensity (p=0.6228). This study showed that risk of recurrent disease is high in NHLs, if CD57 positive cells are low in the background. Our results may highlight the utilization of CD57 as a prognostic parameter in the development of new therapeutic strategies against NHL.