Inhibition of T-cell invasion across cultured fibroblast monolayers by phenothiazine-related calmodulin inhibitors: impairment of lymphocyte motilityby trifluoperazine and chlorpromazine, and alteration of the monolayer by pimozide

Phenothiazines inhibit the typical shape changes displayed by activated lym phocytes and thereby their migration through polycarbonate filters. The str ucture activity relationship of this effect is distinct from calmodulin inh ibition Our aim was to study this effect of phenothiazines on lymphocyte mi gration in an environment with living solid tissue cells. We assessed the e ffect of trifluoperazine and chlorpromazine (TFP and CP, two strong inhibit ors of lymphocyte motility) and pimozide (PIM, a much weaker inhibitor of l ymphocyte motility but a strong inhibitor of calmodulin) on invasion of hum an Molt-l T-cells across precultured fibroblast monolayers. As expected inv asion was inhibited by TFP and CP in the micromolar range that also inhibit ed motility. Surprisingly, PIM inhibited monolayer invasion at least as eff iciently as TFP and CP (from 2.25 muM on). Preincubation of the monolayers or the lymphoid cells show that PIM exerted this novel invasion inhibiting effect on the monolayer. TFP acid CP had a much weaker effect on the monola yer. Since these three compounds inhibit calmodulin in the same order, it i s likely that this effect on the monolayer was caused by inhibition of a ca lmodulin-dependent pathway. KN-62, a specific inhibitor of calmodulin-depen dent protein kinase Il acted on the monolayer like PIM, whereas ML-7, a spe cific inhibitor of myosin regulatory light chain kinase, inhibited lymphoid cell motility like TFP and CP. In conclusion, invasion of T-cells across c ellular monolayers is inhibited both by PIM and by phenothiazines like TFP and CPI but via distinct mechanisms: TFP and CP inhibit lymphocyte motility via a calmodulin independent pathway, whereas PIM impairs the monolayer's tolerance for invasion, most likely via a calmodulin and CamKII dependent p athway. (C) 2001 Elsevier Science Inc. All rights reserved.