Role of prolactin in B cell regulation in multiple sclerosis

• Prolactin levels are higher in MS subjects compared to control subjects.
• Prolactin induces increased number of anti-MOG secreting cells.
• Prolactin induces increased levels of BAFF and expression of Bcl-2 and CD40.
• Levels of prolactin correlated inversely with apoptotic B cell percentages.
• Prolactin decreased B cell receptor-mediated activation threshold.

The role of prolactin in MS pathogenesis was investigated. Prolactin levels were higher in MS subjects both during remission and exacerbation compared to control subjects. Prolactin increased JAK2 expression and Stat phosphorylation on B cells, up-regulated anti-MOG antibody secreting cell numbers, BAFF levels, and Bcl-2expression, and down-regulated expression of Trp63. Prolactin levels correlated positively with anti-MOG secreting cell numbers, and negatively with induced apoptotic B cells. Additionally, prolactin decreased B cell receptor-mediated activation threshold, and induced CD40 expression in B cells. These findings suggest that prolactin promotes B cell autoreactivity in MS through different mechanisms.