Figure 5. Monocytes, not B cells, produce the cytokines IL-6, IL-8, TNFα and IL-1β and downregulate HLA-DR in response to pSTBM.

A) 10⁶/ml PBMC from non-pregnant donors (n = 3) were stimulated with 50 µg/ml pSTBM, or left untreated, for 20 hours in the presence of Brefeldin A. Intracellular cytokine analysis was performed to detect production of TNFα, IL-6, IL-8 and IL-1β from either B cells (grey bars) or monocytes (black bars). Data shown is the increase in proportion of cells expressing each cytokine above cytokine production in untreated samples, mean (+/− S.D.). B) pSTBM binding to monocytes, but not B cells, caused down-regulation of HLA-DR, shown by median fluorescence intensity of HLA-DR antibody staining (C), (n = 3; mean +/− S.D.).