ASSESSING THE CELLULAR AND ADHESIVE INTERACTIONS IN IN VITRO MODELS OF MANTLE CELL LYMPHOMA

Abstract

Mantle cell lymphoma (MCL) is a rare lymphoproliferative disorder (LPD) that has very poor survival. Like other LPDs, the neoplastic cells of MCL have an intimate dependence upon accessory cells within haematopoietic tissues. Understanding and exploiting the tissue-relationships of the mantle cells may therefore lead to further new approaches to treatment. This study work has set out to construct an in vitro system to model relevant aspects of the tissue-dependent behaviour of the neoplastic mantle cells, seeking to establish the link between in vitro behaviour and clinical phenotype, and establishing the feasibility of this system to study the effects of different therapeutic interventions. The first experimental chapter employs relevant mouse and human stromal models to mirror the tissue environment of MCL in vivo. Testing relevant agents, the work establishes that the system can identify different behaviour between indolent and aggressive forms of MCL, and demonstrates a particular importance for CD40 ligand both in the proliferation and survival of the neoplastic mantle cells, but shows also how these effects are modulated by the soluble factors interleukin-4 (IL-4) and the toll-like receptor-9 ligand (TLR9-L). The second experimental chapter examines the adhesion molecules expressed on MCL cells. Considerable variation in the level of expression is observed between cases, but overall the cases express particularly high levels of the integrin receptors LFA-1 (detected by alpha chain CD11a) and VLA-4 (detected by alpha chain CD49d). Cases also showed a significant difference in overall adhesion and chemokine-receptor expression between cases that had either a nodal or leukaemic clinical pattern, although no single adhesion molecule was characteristic of clinical phenotype. The final experimental chapter looked at 3-D culture of MCL. Within tissues MCL grows in a 3-D rather than 2-D matrix and it is recognised that cells employ different forms of adhesion and migration within the different spatial environments. This chapter establishes the feasibility of growing cells in 3-D systems and looks at optimal conditions to preserve and examine the cellular characteristics of cells within a 3-D environment. Overall, this thesis demonstrates the feasibility and pathobiological relevance of ex vivo culture of MCL cells giving insights into the factors that drive MCL survival and proliferation and the correlation between in vitro behaviour and clinical phenotype. It is proposed that this work can be expanded to examine therapeutic interventions in the disorder.