Stimulation of murine B cells and macrophages by bovine Beta-Lactoglobulin (BLG)

B cells were isolated by negative selection using magnetic activated cell sorting with anti-Thy 1.2 antibody coated beads. BLG significantly stimulated B cell proliferation by approximately 8 fold. A trace of IL-10 was detected in unstimulated B cells, but when stimulated with BLG, a substantial amount of this cytokine (606.3 pg/mL) was produced. B cells stimulated with BLG also had a 5 fold increase in glutathione level. When tested on a BALB/c macrophage cell line (J774) for nitric oxide (NO) production, IFN-y alone was slightly stimulatory (3.95 μmolar), BLG alone was also slightly stimulatory (7.42 μmolar), but when combined with IFN-y, a marked increase was observed (42.3 μmolar). We have examined changes in the level of Ia expression as well. There was significant expression of Ia determinants with and without BLG in nonactivated J774 macrophages. However, BLG decreased Ia expression by 32% when added to macrophages activated with IFN-y. Under these same conditions there was a major increase in NO production. Conversely, when BLG was added to B cell cultures, there was a 50% Increase in Ia expression. These results indicate that BLG is a significant modulator of macrophage and B cell immune responses in vitro.