Murine T-cell heterogeneity.

Immunoregulatory lymphoid cells that mature under the influence of the thymus gland (T cells) have been implicated to a major extent in the induction or at least the perpetuation of malignant neoplasms in man. Those T cells are thought to inactivate, suppress, or neutralize the normally occurring tumoricidal effector cells and thereby facilitate the unchecked growth of the neoplasm; the term "suppressor T cells" is therefore used to denote their individual activity. This concept implies that there is a balance between the effector cells and the suppressor cells in healthy subjects and that perhaps enrichment and activation of those cells involved in the defense against neoplastic growth, and specific depletion and elimination of those cells involved in suppression or inactivation of the former in patients with malignant diseases, may provide new modalities in cancer immunotherapy. Most of the studies that form the basis of this concept have been derived in animal models, particularly the mouse. The existence of cell-surface markers which have been used as phenotypic tools has provided the knowledge that distinct subpopulations of lymphoid cells do exist. The phenotypic characterization of lymphoid cells involved in functionally dinstinct immunologic events has been the object of intensive investigation. Therefore, the purpose of this paper is to briefly document our current knowledge of the functional heterogeneity that exists in murine T cells based on the differential expression of these cell-surface markers.