The role of lymphoid cells in hematopoietic regulation

The present review has summarized evidence supporting the existence of different lymphoid subsets with opposing effects on hematopoietic cell growth (Table 1); specifically; a) growth stimulation resulting from the release of interleukins and granulocyte-macrophage colony-stimulating factor (GM-CSF) by particular subsets of lymphocytes and resting natural killer (NK) cells and b) growth inhibition resulting from the release of interferon (IFN) and tumor necrosis factor (TNF) by stimulated NK, B and lymphokine-activated killer (LAK) cells and inhibitory T lymphoid subsets. The systematic examination of the physiologic relevance of lymphoid subsets would add an important element to a more comprehensive model of hematopoietic regulation that might hold promise in future clinical applications.