Altered distribution of T lymphocyte subsets in lithium-treated patients

37 lithium-treated patients, 6 prelithium patients and 12 healthy volunteers were studied regarding relative and absolute numbers of peripheral blood lymphocytes, T lymphocytes and T lymphocyte subsets defined with monoclonal antibodies (OKT4, OKT8). Prelithium patients did not differ significantly from healthy volunteers. The relative and absolute numbers of OKT4 cells were lower in lithium-treated patients than in the controls. The relative number of OKT8 cells increased with increasing duration of lithium therapy. Abnormally high as well as low OKT4/OKT8 ratios were found in lithium-treated patients. OKT4/OKT8 ratios were negatively correlated to the duration of lithium therapy. The urinary concentration capacity was significantly lower in patients with low OKT4/OKT8 ratio than in the other lithium-treated patients. It is concluded that lithium in therapeutic doses may have immunomodulatory effects.