CD40-activated B cells express full lymph node homing triad and induce T-cell chemotaxis: potential as cellular adjuvants

Abstract

CD40-activated B cells (CD40-B cells) have previously been introduced as an alternative source of antigen-presenting cells for immunotherapy. CD40-B cells can prime naive and expand memory T cells, and they can be generated in large numbers from very small amounts of peripheral blood derived from healthy individuals or cancer patients alike. Administration of CD40-B cells as a cellular adjuvant would require these cells to migrate toward secondary lymphoid organs and attract T cells in situ, processes guided by specific chemokines and chemokine receptors. Here, we demonstrate that primary, human CD40-B cells express a pattern of adhesion molecules and chemokine receptors necessary for homing to secondary lymphoid organs and have the capacity to migrate to cognate ligands. Furthermore, we show that CD40-B cells express important T-cell attractants and induce strong T-cell chemotaxis. These findings further support the use of CD40-B cells as cellular adjuvant for cancer immunotherapy.

Figure 1.

Lymph-node homing phenotype of CD40-activated B cells. (A) Expression of lymph node homing receptors on CD40-B cells. First row: Expression by CD40-activated B cells after 14 days of culture; similar results were obtained at later time points. Second row: Expression by unstimulated B cells. Third row: Expression by immature monocyte-derived DCs. Fourth row: Expression by monocyte-derived DCs upon maturation with anti-CD40L/TNF-α. One representative experiment of at least 8 is shown. (B-C) Migration of CD40-B cells. Total number of CD40-B cells in bottom chamber of Costar transwell plate after 2-hour migration through a 5-μm filter. Migration was determined for different concentrations of chemoattractants: (B) Ligand of CXCR4: CXCL12. (C) Ligands of CCR7: CCL21 (□) and CCL19 (▪). Mean values are shown; at least 6 independent experiments were performed.

Figure 2.

CD40-activated β cells induce T-cell migration. (A) Migration of T cells induced by supernatant from CD40-B cell cultures. CD4⁺ and CD8⁺ T cells were migrated for 2 hours through a 5-μm filter into the lower chamber of transwell plates containing supernatant from immature and mature monocyte-derived DCs and CD40-B cells as well as chemokines SDF-1α and SLC. Mean values of migration above background (cells spontaneously migrating to normal culture medium) in at least 7 independent experiments are shown. (B) Migration of T-cell subpopulations to supernatants from APC cultures. CD4⁺ were migrated for 2 hours through a 5-μm filter into the lower chamber of transwell plates containing SLC, SDF-1α, and supernatants from CD40-B, immature, and mature monocyte-derived DCs. T-cell subpopulations before and after migration are shown. From bottom to top: T naive (▪), T effector memory (), T central memory (), and T effector memory RA⁺ (□). Mean values of 3 independent experiments are shown.