Assessment of the influence of peripheral blood mononuclear cell stimulation with Streptococcus pneumoniae polysaccharides on expression of selected Toll-like receptors, activation markers and Fas antigen in patients with chronic lymphocytic leukemia.

Abstract

Since 2012, both the 13-valent pneumococcal conjugate vaccine (PCV13) and the 23-valent pneumococcal polysaccharide vaccine (PPV23) have been recommended for pneumococcal infection prevention in patients with chronic lymphocytic leukemia (CLL). Available literature data indicate that leukemic cells may respond to the presence of pathogens through specific Toll-like receptors (TLR). The aim of the study was to assess the effect of in vitro PPV23 stimulation of peripheral blood mononuclear cells (PBMCs) on expression of TLR-2, TLR-4, CD25, CD69, and CD95 on the surface of CD3+ T cells and CD19+ B cells in CLL patients. A total of 30 previously untreated patients with CLL, stage 0 according to the Rai classification, were included in the study. PBMCs obtained from each patient were cultured with and without PPV23 antigens. After 24-, 48-, and 72 h cultures, the viable cells underwent labeling with fluorochrome-conjugated monoclonal antibodies, and were analyzed using a flow cytometer. Between 24 h and 72 h (p=0.002) stimulation with PPV23 and between 48 h and 72 h (p=0.034) stimulation with PPV23 the frequencies of CD3+TLR-2+ cells were diminished. Increase of the value of the percentage of CD19+CD69+ cells was observed after 24 h (p=0.003), 48 h (p=0.025) and 72 h (p=0.012) of stimulation with PPV23. Stimulation with PPV23 led to an increase of the percentage of CD19+CD95+ cells after 24 h (p=0.003), 48 h (p=0.015), and 72 h (p=0.006). We found that both T and B cells respond to antigens of PPV23 by inducing TLR-dependent pathways, lymphocyte activation and CD95 expression.