CD27⁺CD21^low, compared with CD27⁻ and CD27⁺CD21^high, G6⁺ B cells from HCV⁺MC⁺ patients demonstrate decreased differentiation to IgM RF-secreting plasmablasts on CD40L/IL-2/IL-10 stimulation. Analyses of 5 HCV⁺MC⁺ patients' B cells are shown. B cells from LDU 125 were collected 10 months after the cells collected for the microarray and primary immunophenotyping experiments. CD27⁺CD21^low, CD27⁺CD21^high, CD27⁻CD21^low, and CD27⁺CD21^high G6⁺ B cells were bulk-sorted and plated in a 96-well dish. For patient LDU 125, CD27⁺CD21^low, CD27⁺CD21^high, CD27⁻ G6⁺ B cells and total G6⁻ B cells were sorted. After 6 days of incubation in media supplemented with CD40L, IL-2, and IL-10, cells and supernatants were collected. (A) IgM enzyme-linked immunospot of stimulated B cells. (B) IgM ELISA of cell culture supernatants. (C) IgM RF ELISA of cell culture supernatants.