We first established B cell cultures from the peripheral blood of melanoma patients to study antibody responses to cancer ( Figure  S1 ). In agreement with a previously published report, we detected a reduced memory B cell subset in melanoma patients. Melanoma patient and healthy volunteer B cells were cultured with B cell purity greater than 90%. Following EBV transformation and activation with a TLR9 agonist, patient B cells were observed to proliferate in culture for over eight weeks and 80% of the cells in these cultures were IgG positive. B cell cultures derived from healthy volunteers (n = 5) and melanoma patients (n = 5) had comparable mean antibody titers after 18 days, ranging from 1 to 7 mg from each individual, with an overall mean of 2.5 mg (95% CI = 2.3 to 2.7) per culture arising from 500 B cells per well. We therefore established antibody-secreting cultures from melanoma patients with comparable rates of IgG secretion to healthy volunteers.