Document Type: Original Article
Department of Immunology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
Shiraz Institute for Cancer Research, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
Department of Pathology, Shiraz Central Hospital, Shiraz, Iran
Breast Diseases Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
Background: B cells can increase the expression of granzyme B in CD8+ T cells through 4-1BBL/4-1BB interaction and promote anti-tumor immunity. Objective: To investigate the expression of 4-1BBL on B cells in the breast tumor draining lymph nodes (TDLNs) and its association with disease parameters. Methods: Using Ficoll-Hypaque gradient centrifugation, mononuclear cells were isolated from axillary lymph nodes of 42 patients. Cells received 4 hours of PMA/Ionomycin stimulation, in vitro. Both unstimulated and stimulated cells were stained with anti‒CD19 and anti‒4-1BBL antibodies and subjected to flow cytometry. Results: 4-1BBL expression was detected on 2.8 ± 1.7% of unstimulated B cells, while 27.4 ± 11.9% of B cells expressed this co-stimulatory molecule following stimulation. In steady state, the percentage of 4-1BBL+ B cells was not associated with cancer characteristics. However, in patients with invasive ductal carcinoma, the percentage of 4-1BBL expressing B cells in stimulated condition had a decreasing trend in grade III, compared to grade II+I. In addition, significantly higher frequency of 4-1BBL+ B cells was seen in the TDLNs of ER+ or PR+ compared with ER‒ or PR‒ patients (p=0.021 and p=0.015, respectively). No significant associations were observed between the frequency of 4-1BBL+ B cells and the number of involved LNs, Her2 expression or disease stage. Conclusions: The frequency of 4-1BBL+ B cells significantly increased following a short time activation, and showed relative and significant associations with tumor grade and estrogen receptor status, respectively. More investigations are required to evaluate the potential of 4-1BBL+ B cells for use in immunotherapy.