Circulating T-cell subpopulations in lithium-associated granulocytosis

Granulocytosis is a common feature in patients undergoing lithium therapy. With increasing evidence that T lymphocytes play a role in the control of granulopoiesis, we have investigated the effect of lithium administration on circulating levels of T helper and T suppressor cells, as identified by monoclonal antibodies, to determine whether lithium-induced granulocytosis is mediated through changes in peripheral blood T cell subsets. Lithium carbonate was administered to 10 subjects over a 2 week period. Differential leucocyte counts and T, B, T helper and T suppressor lymphocyte enumerations were performed prior to administration of lithium (Day 1) and on 2 occasions (Day 7 and 14) during ingestion of the drug. Ten healthy control subjects were similarly investigated. Small, but significant elevation (p less than 0.05) in neutrophil counts at 7 and 14 days were observed in subjects taking lithium, serum lithium levels at these times were 0.56 +/- 0.27 and 0.68 +/- 0.17 mmol/l, respectively; lymphocyte and monocyte levels were unaffected. The percentages and absolute numbers of circulating T, B, T helper and T suppressor lymphocytes were not significantly altered (p greater than 0.05) during lithium administration and did not differ significantly (p greater than 0.05) from those recorded for the control group. We were thus unable to demonstrate that short-term lithium administration induced changes in the circulating levels of T helper (OKT4+) or T suppressor (OKT8+) cells.