An investigation into the Humoral Response in Cutaneous Melanoma
Melanoma is a cancer which develops from the malignant proliferation of melanocyte cells. There are 4 subtypes, of which cutaneous melanoma (CM), is the most prevalent (Rabbie et al., 2019). The T cell immune response in melanoma has been well defined, however, the B cell response is much less understood (Rodgers et al., 2022). Lymphoblastoid cell lines (LCLs) are immortal B cells which have been transformed via Epstein Barr virus (EBV) infection (Mrozek-Gorska et al., 2019). It was hypothesised that LCLs derived from stage III/IV CM patients can provide a renewable source of functional B cells and that IgG, present in melanoma patients, will have a functional role in tumour control. It was also investigated if: LCLs and melanoma cell lines derived from III/IV CM patients secrete IgG; if IgG is internalised by melanoma cells; and lastly if gating strategies defined by Sanz et al. (2019) were suitable for defining the B cell subtype of LCLs. Results showed some LCLs secreted IgG, while others did not. It was also shown that it is likely that the source of these IgG is a transient pre-plasmablast lineage. The IgG produced was likely an artifact of EBV transformation rather than being melanoma patient specific. Furthermore, melanoma cells were found not to secrete IgG, suggesting that previously observed melanoma patient specific IgG is derived from B cells rather than tumour. Thus, while LCLs are useful for several experimental protocols, they are unlikely sufficiently physiologically relevant to be used in the investigation of melanoma specific B cell functions. Lastly, the gating strategies investigated did not appear to be suitable for B cell subtyping of LCLs due to the observed populations not fitting the defined gates, however, the Sanz et al. (2019) gating strategy may be more suitable for the B cell subtyping of PBMCs.
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