Effects of pH, Charybdotoxin, and PC12 cells on Jurkat T-cell proliferation

Abstract

Abstract Neuroimmunological diseases involve T-cell attacking neurons. We showed previously that acid-sensing ion channels (ASICs) and voltage-gated channels (Kv) from different cells can interact leading to inhibition of Kv. We hypothesized that this interaction may exist between Kv of Jurkat T-cells (JTL) and ASICs of PC12 cells (neuronal model), and that this interaction is pH- and Charybdotoxin (ChTX)-dependent. JTL were seeded on top of confluent PC12, or without PC12. The effects of 200 nm ChTX and pH 7.2 on JTL doubling time (DT) were tested. Without PC12, DT was 12.2±0.5h at pH 7.4, 25.6±1.1h with ChTX, and 17.0±1.0h at pH 7.2; in ChTX at pH 7.2, DT was 40.8±5.0h. With PC12, JTL DT was 34.1±2.9h at pH 7.4, 30.1±2.3h with ChTX, and 20.7±1.8h at pH 7.2; in ChTX at pH 7.2, DT was 32.2±1.8h. Paired comparisons without PC12 show that DT was significantly longer at pH 7.2 vs pH 7.4 and in ChTX at pH 7.4; pH 7.2 and ChTX synergistically increased DT vs pH 7.2 and vs ChTX at pH 7.4. With PC12, all corresponding DTs were significantly longer. Paired comparisons showed that at pH 7.2 DT was significantly shorter than at pH 7.4, opposite to without PC12. This can be potentially explained by lower pH relieving inhibition of Kv on JTL by the ASICs on PC12. At pH 7.4, ChTX did not have any effect possibility due to JTL’s Kv already blocked by PC12’s ASICs, and at pH 7.2 ChTX inhibited the free Kv. Thus, both acidic pH and ChTX independently slow down JTL proliferation, and in the presence of PC12, effects of low pH and ChTX are consistent with ASIC-Kv interaction. We speculate that ASICs expressed in APCs and Kv in lymphocytes may be a new unrecognized interaction in the immunological synapse, and disruption of neuronal ASIC-lymphocytic Kv interaction may play a role in autoimmune disease.