Objective: To evaluate lymphocyte activation following mitogen and cyclosporin A (CsA) administration in peripheral blood of hyperthyroxinaemic and hypothyroid patients.
Materials and methods: Lymphocyte activation was evaluated by determining blastogenesis in 48 h cultured blood lymphocytes obtained from eight hyperthyroxinaemic and eight hypothyroid patients, following phytohaemagglutinin (PHA)-induced stimulation in the absence or presence of CsA. Twelve healthy volunteers served as controls.
Results and conclusions: Lymphocytes from hypothyroid patients exhibited reduced response to PHA and lower sensitivity to CsA compared with control, which could be attributed to their reduced activation capability coexisting with hypothyroidism. In hyperthyroxinaemic samples, the actions of high CsA concentrations were mostly targeted toward activated lymphoblasts. Considering the cellular targets that thyroid hormones and CsA may share, the therapeutic implications of their cross-talk need careful consideration.