Table 2.

Prolactin effects on cells of the immune system

Immune cell	Prolactin effect
Macrophages	Enhances release of reactive oxygen intermediates and pro‐inflammatory cytokines such as TNF‐α, IL‐1β, IFN‐γ, and IL‐12 In very high concentrations enhances secretion of IL‐10 Stimulates secretion of chemokines like MIP‐1 αIP‐10, and MCP
Granulocytes	Up‐regulates inflammation‐related genes such as iNOS and IRF‐1 Activates STAT1 and p38 MAPK intracellular pathways
Natural killers cells	Stimulates release of IFN‐γ Stimulates cell proliferation and cytotoxic activity
Dendritic cells	Low levels enhance expression of MHC class II and of stimulatory molecules CD80/CD86 Promotes maturation to functional antigen‐presenting cells
B cells	Stimulates cell proliferation and IgM and IgG secretion Promotes B‐cell auto‐reactivity through increased JAK2 expression and STAT phosphorylation and up‐regulation Decreases B‐cell apoptosis by increasing production of BAFF and Bcl‐2 expression and decreasing Trp63expression Decreases B‐cell receptor‐mediated activation threshold Induces CD40 expression
T cells	Supports proliferation, survival and acts as an autocrine factor Promotes adhesion to activated endothelial cells by integrins LFA‐1 and VLA‐4

BAFF, B‐cell activating factor; Bcl‐2, B‐cell lymphoma 2; iNOS, induced nitric oxide synthase; IP‐10, interferon‐γ‐induced protein; IRF‐1, interferon regulatory factor‐1; LFA‐1, lymphocyte function‐associated antigen‐1; MCP‐1, monocyte chemoattractant protein‐1; MIP‐1α, macrophage inflammatory protein‐1α; Trp 63, transformation‐related protein 63; VLA‐4, very late antigen‐4.