A role for B cells in facilitating defense against an NK cell-sensitive lung metastatic tumor is revealed by stress.

Stressors impair immune defenses and pose risks among cancer patients. Natural Killer cells are not the sole immune defense against tumor development. Utilizing an NK-sensitive tumor model, this study evaluated immune effects to stress and determined whether lung metastasis resulted from B cells' inability to augment tumorlytic function. Lung metastasis directly correlated with delayed lung B cell accumulation compared to NK, and T cells. Decreased interleukin-12 cytokine and CD80+ molecule expression by B cells correlated with decreased tumor lysis and increased tumor development. Thus, tumor defenses in the lung given stress exposure can depend on the B cell function.