Effect of chromium and cobalt ions on primary human lymphocytes in vitro

Cobalt-chromium (Co-Cr) alloy metal-on-metal hip resurfacing is increasingly common among younger more active patients suffering from osteoarthritis. Recent reports have increased awareness of metal ions leaching from metallic articulations; this ion exposure may have adverse effects on the immune system. As previous studies reported alterations in lymphocyte number and function in patients with Co-Cr implants, we investigated effects of clinically relevant concentrations of Cr⁶⁺ and Co²⁺ on primary human lymphocytes in vitro. Here, both resting and activated (anti-CD3 ± anti-CD28 antibodies) primary human lymphocytes were exposed to Cr⁶⁺ or Co²⁺ (0.1–100 µM). Following 24 or 48?h of exposure, cell viability, proliferation, cytokine [interferon-γ (IFNγ and interleukin-2 (IL-2)] release, and apoptosis (with and without pre-treatment of cells with a caspase-3 inhibitor) were assessed. Exposure to 10 and 100 µM Cr⁶⁺ significantly decreased cell viability and increased apoptosis in both resting and activated lymphocytes. Cell proliferation and cytokine release were also significantly reduced in activated lymphocytes following exposure. The exposure of resting lymphocytes to 100 µM Co²⁺ resulted in significant decreases in cell viability accompanied by a significant increase in apoptosis. Activated lymphocytes also showed this response after exposure to 100 µM Co²⁺; in fact, activated cells were significantly more sensitive to Co²⁺ toxicity. Exposure to 10 µM Co²⁺ led to significant decreases in cell proliferation and cytokine release, but no significant increase in apoptosis, in activated cells. The results indicate that exposure to high concentrations of metal ions initiate apoptosis that results in decreased lymphocyte proliferation. IL-2 release is inhibited by both metal ions at concentrations that are not overtly toxic. However, metal ion concentrations not directly cytotoxic to lymphocytes may affect events at a molecular level, thereby impeding lymphocyte proliferation. Hence, this may contribute to altered immune system function in patients with Co-Cr implants.     

Effect of cobalt and chromium ions on human MG-63 osteoblasts in vitro: morphology, cytotoxicity, and oxidative stress

Recent studies demonstrated that Co(2+) and Cr(3+) ions induced cell mortality, TNF-alpha secretion, and oxidation of proteins in macrophages. However, little is known about the effects of corrosion products on the osteogenic cells, which have a crucial role in controlling bone remodeling. The aim of the present study was to investigate the effect of Co(2+) (0-10 ppm) and Cr(3+) (0-150 ppm) on human MG-63 osteoblast-like cells in term of cytotoxicity and oxidative stress. Microscopic analysis demonstrated changes in shape, size, and number of cells. Co(2+) had a greater effect on these parameters than Cr(3+). Cell counting showed a significant decrease in the number of MG-63 osteoblasts in a time- and dose-dependent manner, with Co(2+) more toxic than Cr(3+). The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) analysis also showed a decreased cellular activity in presence of Co(2+) and Cr(3+) ions. Oxidized and nitrated proteins, two markers of oxidative stress, were detected as single bands and revealed time- and dose-dependent protein modifications. We also studied the expression of three antioxidant enzymes. The expression of heme oxygenase-1 was increased by both ions after 24h, before decreasing gradually thereafter. Glutathione peroxidase expression was also increased in a concentration- and time-dependent manner by both Co(2+) and Cr(3+) ions. Co(2+) decreased catalase expression while Cr(3+) increased it in a dose- and time-dependent manner. In conclusion, this study demonstrated that Cr(3+) and Co(2+) have a cytotoxic effect on MG-63 osteoblasts and have the potential to modify their redox state.     

Induction of protein oxidation by cobalt and chromium ions in human U937 macrophages

Metal particles and ions from hip prostheses have the potential to induce the production of reactive oxygen species (ROS), making them prime suspects for disturbing the cellular balance of oxidants/antioxidants (redox state of the cell). To better understand the cellular effect of metal ions from metal-on-metal prostheses, the aim of this study was to examine the effect of cobalt (Co2+) and chromium (Cr3+) ions on protein oxidation in human U937 macrophages. Protein oxidation was measured by Western blot using antibodies directed against dinitrophenylhydrazine (DNP)-derivatized protein carbonyls, the most commonly measured products of protein oxidation in biological samples. Three DNP-derived proteins were detected. The first has a molecular weight of 16 kDa and is expressed at a very low level. The second has a molecular weight of 48 kDa and its level is not regulated by metal ions. The third is a 69 kDa protein and its level is regulated by Co2+ and Cr3+ ions. Therefore, the last band served as a marker of protein oxidation in the present study. Results showed that Co2+ and Cr3+ ions induced a time- and dose-dependent protein oxidation reaching 6.5 and 2.9 times the control after 72 h, respectively, which were inhibited by the antioxidant glutathione monoethyl-ester. Finally, results showed that the oxidized proteins are mainly found in the cytoplasmic fraction of the cells and are absent from the nucleus. In conclusion, our results suggest that metal ions from metal-on-metal prostheses have the potential to modify the redox state of cells both locally (periprosthetic environment) or systematically (circulating cells). The long term effect of these ions on protein oxidation in vivo remains to be investigated.     

Comparative genotoxicity of cobalt nanoparticles and ions on human peripheral leukocytes in vitro

Owing to the increasing development of nanotechnology, there is a need to assess how engineered nanomaterials can interact with living cells. The main purpose of the present study was to assess whether metal cobalt nanoparticles (CoNP 100-500 nm) are genotoxic compared to cobalt ions (Co(2+)). Uptake experiments were carried out by incubating peripheral blood leukocytes (PBLs) with (57)Co(2+) (added to stable Co(2+) 10(-2) M to obtain concentrations in the range of 10(-5) to 10(-4) M) or with (60)CoNP for 24 and 48 h. Whereas intracellular Co(2+) showed slight or no variations over the baseline levels, CoNP were taken up efficiently leading to intracellular CoNP concentrations of 485 +/- 106.1 and 970 +/- 99 fg per cell after 24 and 48 h, respectively. The genotoxicity end points considered in this study were the frequency of binucleated micronucleated (BNMN) cells and the percentage of tail DNA (% Tail DNA) fragmentation by means of the comet assay. Genotoxic effects were evaluated by incubating PBLs of three healthy donors with subtoxic concentrations (10(-5) to 8 x 10(-5)M) of Co(2+) in the form of cobalt chloride, CoNP and 'washed' CoNP, the latter to exclude any interference by Co(2+). On a group basis, Co(2+) induced a clear trend in the increase of the BNMN frequency, whereas CoNP showed only minor changes. Moreover, we observed a high variability among donors in the induction of micronuclei. The comet assay showed a statistically significant dose-related increase in % Tail DNA for CoNP (P < 0,001), whereas Co(2+) did not induce significant changes over control values. These findings suggest that nanosized Co can be internalized by human leukocytes and can interact with DNA leading to the observed genotoxic effects, which are, however, modulated both by donor's characteristics and/or by Co(2+) release.     

Quantitative analysis of macrophage apoptosis vs. necrosis induced by cobalt and chromium ions in vitro

The potential toxicity of metal ions in tissues surrounding metal-metal hip replacements is a cause for concern. Previous studies conducted in our laboratory demonstrated that Co(2+) and Cr(3+) induce TNF-alpha secretion in macrophages, as well as cell mortality. However, the degree of apoptosis and necrosis remained to be investigated. The aim of the present study was to quantify the rate of macrophage mortality by apoptosis vs. necrosis induced by Co(2+) and Cr(3+). J774 mouse macrophages were incubated in growth medium containing 0-10 ppm Co(2+) and 0-500 ppm Cr(3+) for 24 and 48 h under conventional cell culture conditions. Transmission electron microscopy, flow cytometry (Annexin-V fluorescein isothiocyanate/propidium iodide assay) and a specific cell death detection ELISA were used to illustrate cell death and differentiate between apoptotic and necrotic cells. Cell culture exposed to low concentrations of Co(2+) (0-6 ppm) revealed a low degree of mortality. In contrast, at the highest concentrations (8-10 ppm), late apoptosis occurred within 24 h. After 48 h, however, there was a clear evidence for an increase in the rate of necrosis while apoptosis occurred at much lower rate. Macrophages exposed to Cr(3+) demonstrated a predominance of apoptosis after 24h. At concentrations lower than 250 ppm, early and late apoptosis occurred at the same rate. At higher concentrations (250-500 ppm), the number of early apoptotic cells decreased in favor of late apoptosis. After 48 h, lower concentrations of Cr(3+) (150 ppm) induced a higher degree of early apoptosis than after 24 h, and some necrosis. At higher concentrations, the percentage of early apoptotic cells decreased, while necrosis became predominant over late apoptosis. In conclusion, this study demonstrates that macrophage mortality induced by metal ions depends on the type and concentration of metal ions as well as the duration of their exposure. Overall, apoptosis was predominant after 24 h with both Co(2+) and Cr(3+) ions, but high concentrations induced mainly necrosis at 48 h. These results point to the potential for these ions of inducing tissue damage by necrosis if present in large concentrations in vivo.     

Effect of cobalt and chromium ions on bcl-2, bax, caspase-3, and caspase-8 expression in human U937 macrophages

The bcl-2 and caspase families of proteins play a central role in the modulation of apoptosis. The purpose of this study was to analyze the effect of Co(2+) and Cr(3+) ions on the expression of bcl-2, bax, caspase-3 and caspase-8 to better understand the mechanisms leading to ion-induced apoptosis in macrophages. U937 human macrophages were exposed to Co(2+) and Cr(3+) ions. The expression of proteins was measured by Western blot while caspase activities were measured by colorimetric assay. Results show that Co(2+) ions inhibited bcl-2 expression with significant effect (p<0.05) after 16 h and a maximal 52% inhibitory effect after 24 h. Co(2+) stimulated bax expression with a significant stimulation (p<0.05) after 8 h and a maximal 1.75-fold increase after 16 h. Co(2+) also stimulated the expression of the active fragment of caspase-3 as well as caspase-3 activity maximal increase after 24 h. Co(2+) ions had no effect on caspase-8 expression or activity.Cr(3+) ions inhibited bcl-2 expression with significant effect (p<0.05) after 16 h and a maximal 43% inhibitory effect after 24 h. Cr(3+) stimulated bax expression with significant stimulation (p<0.01) after 8h and a maximal 2.25-fold increase after 24 h. Cr(3+) ions also stimulated the expression of the active fragments of caspase-3 and -8, as well as the activities of both proteases. The effect of Cr(3+) ions on the expression of both caspase active fragments was maximal after 16 h incubation. In conclusion, our results suggest that the modulation of the expression of proteins from the bcl-2 and the caspase families of proteins are implicated in the induction of macrophage apoptosis by Co(2+) and Cr(3+) ions.     

Effect of analogs of cinanserin on human lymphocytes in vitro

Cinanserin, 2-(3-dimethylaminopropylthio)cinnamanilide, was compared in phytohemagglutinin (PHA)-treated human lymphocytes in vitro to two analogs, 2-(3-dimethylaminopropoxy)-5-methylcinnamanilide (SQ 11,276) and 5-tert.-butyl-2-(3-dimethylaminopropoxy) cinnamanilide (SQ 11,332). These analogs, like cinanserin, exhibit immunosuppressive activity but, unlike cinanserin, possess low antiserotonin activity.Within 1–1.5 hours after addition of the drugs (0.15 mM), incorporation of³H-uridine,¹⁴C-leucine, and³H-thymidine into a macromolecular fraction of PHA-treated cells were inhibited, in an increasing order, by cinanserin, SQ 11,276 and SQ 11,332. At this concentration cellular recovery and viability wre unaltered by cinanserin and SQ 11,276 and substantially decreased by SQ 11,332. SQ 11,332 was less cytotoxic at lower concentrations and 4–7 times more active than cinanserin as an inhibitor of the incorporation of the nucleosides into the macromolecular fraction.     

Cobalt and chromium ions induce nitration of proteins in human U937 macrophages in vitro

The in situ localization of nitrotyrosine, a product of the nitration of tyrosine residues by peroxynitrite, in the interface membranes from Co--Cr--Mo and Ti--Al--V prostheses provided evidence of nitric oxide-induced oxidative damage in the periprosthetic environment. In the present study, we compared the effects of different wear products from hip prostheses on the nitration of proteins in macrophages in vitro. Nitration of proteins was measured by Western blot using a polyclonal antibody directed against nitrotyrosines. Results showed that Co(2+) and Cr(3+) ions induced the nitration of a 79 +/- 4 kDa protein in a time- and dose-dependent manner. Indeed, the stimulation was significant (p < 0.05) after 24 h with 10 ppm Co(2+) and reached a plateau level between 48 and 72 h. With Cr(3+), the stimulation was significant (p < 0.05) only after 48 and 72 h. The effect of both Co(2+) and Cr(3+) ions was inhibited by glutathione monoethyl-ester that provides protection against oxidative stress. However, ultrahigh-molecular-weight-polyethylene and alumina ceramic particles had no significant effect on the nitration of proteins. Finally, the results showed that nitrated proteins are mainly found in the cytoplasmic fraction of cells and are absent from the nucleus. In conclusion, our results show that Co(2+) and Cr(3+) ions induce the nitration of cytoplasmic proteins in human U937 macrophages, suggesting that metal ions from MM prostheses have the potential to modify protein function in the periprosthetic environment and in circulating cells.     

Effect of clover extract on proliferation of human and murine lymphocytes in vitro

Department of Botany, I. M. Sechenov Moscow Medical Academy. Laboratory of Cellular Immunity, Oncologic Scientific Center, Russian Academy of Medical Sciences, Moscow. (Presented by Academician of the Russian Academy of Medical Sciences N. N. Trapeznikov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 114, No. 11, pp. 520–521, November, 1992.     

TNF-alpha secretion and macrophage mortality induced by cobalt and chromium ions in vitro-qualitative analysis of apoptosis

Metal ion toxicity is a major cause for concern in metal-metal hip replacements. A previous study in our laboratory demonstrated that Co(2+) and Cr(3+) induce macrophage apoptosis in vitro at 24h, with the implication of a caspase-3 pathway. The aim of the present study was to look at the effect of a prolonged incubation time on macrophage response with regards to TNF-alpha secretion and macrophage mortality, more specifically apoptosis. J774 macrophages were exposed for up to 48 h to 0-10 ppm Co(2+) and 0-500 ppm Cr(3+). ELISA results demonstrated that Co(2+ )and Cr(3+) induced a concentration- and time-dependent increase of TNF-alpha secretion, but a decrease at the highest concentrations of Cr(3+) (350-500 ppm). This decrease was most likely due to a high toxicity of Cr(3+) at such concentrations. Higher levels of TNF-alpha were observed with Co(2+) than Cr(3+), demonstrating a higher stimulatory effect of this ion. Trypan blue and flow cytometry results demonstrated that both Co(2+) and Cr(3+) ions induce macrophage mortality in a dose- and time-dependent manner. The number of cells decreased when ion concentrations increased, especially at 48 h. In parallel with the TNF-alpha results, Co(2+) was more toxic than Cr(3+) since the maximal effects were reached with lower concentrations (8-10 ppm vs. 350-500 ppm, respectively). DNA analysis demonstrated that both Co(2+) and Cr(3+) ions induce macrophage apoptosis, with a stronger signal at 24h than at 48 h, suggesting the presence of more necrosis after 48 h. PARP cleavage, another marker of apoptosis, was observed at both 24 and 48 h, with a maximum intensity at 48 h and with the highest concentrations of ions. In conclusion, this study demonstrates that both Co(2+) and Cr(3+) ions can induce the release of TNF-alpha and macrophage mortality in a dose- and time-dependent manner. More specifically, Co(2+) and Cr(3+) ions induced apoptosis after both 24 and 48 h incubation, although DNA analysis suggested the presence of necrosis at 48 h. The relative importance of apoptosis and necrosis in the induction of macrophage mortality by these metal ions remains to be investigated.     

Effect of in vitro x-irradiation on human peripheral blood T and B lymphocytes.

The effect of in vitro irradiation with increasing in logarythmic progress X-ray doses on lymphocyte viability and on T and B lymphocyte populations was studied in normal adults, patients with myasthenia gravis and in patients undergoing long-term steroid therapy. Decrease in numbers of lymphocytes carrying T or B lymphocyte surface markers was higher than viable cell loss. The decrease showed no linear correlation with X-ray doses applied, which might reflect the existence of radioresistant T and B lymphocytes. A higher so called early radiosensitivity of B lymphocytes was demonstrated. In patients with myasthenia gravis early radioresistance of T lymphocytes was detected. In patients undergoing long-term steroid therapy, an increase in numbers of cells lacking markers of any of lymphocyte populations was found in parallel with a decrease in T lymphocyte number which, in these patients, showed a higher radiosensitivity.     

Effect of metalloproteinase from Staphylococcus aureus on in vitro stimulation of human lymphocytes

Metalloproteinase (MP) produced by the majority of Staphylococcus aureus strains exerts, in a wide concentration range (0.1-100 micrograms/ml), no cytotoxic action on mononuclear leukocytes of human peripheral blood. The enzyme itself does not appreciably stimulate proliferation and differentiation of lymphocytes in culture, but affects the stimulation of both T and B lymphocytes by polyclonal activators. The action is dose-dependent. High doses of MP (100 micrograms/ml) lower the blastic transformation after stimulation with Con A, SpA, NDCM, S. aureus strain Wood 46 and with suboptimal doses of PWM. Optimal concentrations of the enzyme potentiate the stimulation of lymphocytes by PWM, PHA, S. aureus strains Cowan 1 and Wood 46, and by NDCM. The same potentiation effect was achieved whether the enzyme was added concurrently with the mitogen or 18 h later. This implies that the beginning of cell activation is not affected. A high MP concentration decreases the production of Ig in culture after stimulation with PWM whereas lower concentrations of MP enhance this production. Production of Ig after stimulation with NDCM and Wood 46 is decreased by MP. The possible action of exoproteinase from S. Aureus on the immune response during infection is discussed.     

Metal-on-metal bearings in total hip arthroplasties: Influence of cobalt and chromium ions on bacterial growth and biofilm formation

Metal-on-metal (MOM) bearings involving cobalt-chromium (Co-Cr) alloys in total hip arthroplasties are becoming more and more popular due to their low wear. Consequences of corrosion products of Co-Cr alloys are for the most part unclear, and the influence of cobalt and chromium ions on biofilm formation has never been studied. Therefore, the aim of this study was to evaluate how Co-Cr ions affect bacterial growth, biofilm formation, and architecture. A collection of clinically isolated and commercially available bacterial strains were exposed to Co-Cr concentrations as found in serum and above as found in adjacent tissue. Planktonic growth of bacteria was inhibited by concentrations of 200,000/93,000 microg/L Co-Cr. Co-Cr concentrations up to 20/9.3 microg/L as reported to occur in serum revealed no consistent influence on biofilm formation, but higher concentrations of 200,000/93,000 microg/L significantly reduced Staphylococcus aureus and CNS biofilm formation. As indicated by confocal laser scanning microscopy, no dead bacteria were encountered in the biofilms, and the metal ion concentrations used must be classified as growth-inhibiting and not bactericidal. Long-term clinical data on infection rates for Co-Cr MOM-bearings are not yet available, but the current results suggest that Co-Cr ions may yield these prostheses less prone to biofilm formation and subsequent infection.     

The molecular structure of complexes formed by chromium or cobalt ions in simulated physiological fluids

It is well recognized that workers in mines and manufacturers of hard metals in contact with metal ions have increased risk of cancer. However, the various chemical forms of these ions in living organisms are not well characterized, and little is known of how they interact with biological environments. Here, we sought to elucidate the molecular structures formed by cobalt (Co) and chromium (Cr) ions in simulated biological fluids. Transmission electron microscopy observations revealed that Cr(III) formed nanoscale complexes which precipitate in both RPMI 1640 and DMEM high glucose media. However, no complexes were observed with Co(II) and Cr(VI). Energy-dispersive X-ray analysis, elemental analysis, and Fourier transform infrared (FT-IR) spectroscopy indicated that Cr(III) ions act as chelating entities between PO(4) groups, amino acids, and calcium. Although the exact nature of the bonds remains to be investigated, the presence of PO(4) may favor the formation of low energy hydrogen bonds. Interestingly, the nature of amino acids varied in Cr(III) complexes formed in RPMI 1640 compared to those formed in DMEM high glucose. The absence of sulphur in the elemental analysis spectrum suggested that methionine and cystine, two amino acids containing sulphur, are not involved in the formation of Cr(III) complexes. Thus, the lower toxicity of Cr(III) compared to Co(II) and Cr(VI) may be related to the formation of these chemical complexes. These results may bring some insight in understanding the relationship between toxicity and the chelating capabilities of various metal ions in vitro and in vivo.     

Differential effects of human granulocytes and lymphocytes on human fibroblasts in vitro

Polymorphonuclear leucocytes (PMN) were found to damage human fibroblast monolayers. Allogeneic and autochthonous PMN were equally efficient and monolayer destruction (plaque-formation) occurred within 24 hr, as a rule, in the absence of agglutinating substances such as phytohaemagglutinin. Living PMN were not necessary for plaque-formation, since cells heated to 56°C for 30 min or disintegrated by ultrasound were still competent to produce plaques. It is suggested that enzymes enclosed in cytoplasmic granules in the PMN are responsible for plaque-formation. Although the monolayer was destroyed, the target cells were not killed after treatment with PMN, but detached from the surface of the culture vessel into the medium and could be recultivated from the supernatant. Heparin, chondroitin sulphate and trypan blue suppressed plaque-formation by intact and disintegrated PMN, while a variety of metabolic inhibitors or X-rays had no effect.

Lymphocytes from non-immunized donors were also competent to cause destruction of fibroblast monolayers, but this reaction required the presence of phytohaemagglutinin. Heating of the lymphocytes to 48·5°C or ultrasound disintegration abolished the plaque-forming ability, suggesting that living lymphocytes were required. In contrast to PMN, lymphocytes were shown to kill the target cells. PHA-treated lymphocytes were equally cytotoxic to allogeneic and autochthonous fibroblasts and it is suggested that actual target destruction is immunologically non-specific and caused by transformed lymphocytes, which acquire the ability to kill all fibroblast targets regardless of their genotype and the event triggering lymphocyte transformation.

     

Effects of permethrin on human basophils and lymphocytes in vitro

Inflammation Research -     

Effect of isoprinosine on in vitro proliferative responses of human lymphocytes stimulated by antigen

Isoprinosine, a synthetic purine derivative, did not significantly interfere with the thymidine uptake of triggered normal lymphocytes, nor exhibit a detectable mitogenic activity. Isoprinosine was able to significantly enhance specific proliferative responses of human lymphocytes from sensitized donors to soluble antigens. Isoprinosine did not alter the early interaction of human mononuclear cells with 125I-labelled antigen, nor the expression of their membrane receptors for immunoglobulin Fc fragments. The agent could not replace the accessory r?le of adherent cells in proliferative responses to antigens. The enhancing effect of isoprinosine on antigen specific responses of T-cells was observed upon adding the compound on any one of the seven days of culture. Isoprinosine partially restored the inhibited proliferation of lymphocytes cultured in the presence of deoxyadenosine and deoxycoformycin. Data suggest that metabolic changes involving purines may account for the effect of isoprinosine on the expression of T-cell responses.     

反复熔铸对NEO钴铬烤瓷合金金瓷结合性能的影响

背景：NEO钴铬烤瓷合金不含有害物质,但其钴铬烤瓷合金能否回收利用存在争议,反复熔铸对NEO烤瓷合金性能影响的报道较少。 目的：观察反复熔铸对NEO钴铬烤瓷合金金瓷结合力、金相结构、金瓷界面形貌的影响。 方法：根据ISO9693标准,采用真空条件下氩气保护加压铸造方法,用三点弯曲实验测试分别经过1~5次熔铸后NEO钴铬烤瓷合金的金瓷结合能力,金相显微镜观察各代铸件金相结构,扫描电镜观察各代试件金瓷结合界面形貌。 结果与结论：分别经过1~5次熔铸后的NEO钴铬烤瓷合金的金瓷结合能力差异有显著性意义(P < 0.05);随着熔铸次数增加铸件的树枝状结构和晶粒结构逐渐模糊、消失;试件金瓷界面结合逐渐疏松、过渡层厚度增加。提示经过反复熔铸的NEO会明显影响其金瓷结合性能。      

钛离子对T淋巴细胞体外增殖及活化的影响

BACKGROUND: Titanium ions have been proved to stimulate the secretion of bone remodeling-related factors from T lymphocytes; however, the effects of titanium ions on the early activation, intermediate activation, and cell cycle of T lymphocytes remain unclear. OBJECTIVE: To investigate the effects of titanium ions on the proliferation and activation of T lymphocytes in vitro. METHODS: Cell proliferation and cycle test: Jurkat E6-1 T lymphocytes in logarithmic phase were collected and cultured in the medium containing 0 (control), 25 (low concentration), 50 (middle concentration), and 100 μmol/L (high concentration) titanium ions for 24 hours to detect the cell relative proliferation rate and cell cycle. Cell activation trial: Jurkat E6-1 T lymphocytes were divided into two groups that were subdivided into four groups containing 0, 25, 50, and 100 μmol/L titanium ions, respectively with or without phytohemagglutinin (PHA) pre-stimulation. The expressions of CD69 and CD25 were measured after cultured for 24 hours. RESULTS AND CONCLUSION: Titanium ions enhanced T lymphocytes proliferation in a concentration-dependent manner (P < 0.05). Compared with the control group, the percentages of G₀/G₁ phase decreased and the proportions of cells in S and G2/M phase increased significantly in the low, middle and high concentration groups (P < 0.05). The proportion of G₀/G₁-phase cells in the high concentration group was less and the proportion of G₂/M phase cells was higher than those in the middle and low concentration groups (P < 0.05). With PHA pre-stimulation, the expression of CD69 in the high concentration group was higher than that in the middle and low concentration groups (P < 0.05); whereas the difference of CD25 expression was not significant among four subgroups. Titanium ions promoted the expression of CD69 in a concentration-dependent manner (P < 0.05), but there was no CD25 expression in each subgroup without PHA pre-stimulation. To conclude, titanium ions can significantly promote T lymphocyte proliferation and early activation in vitro, and moreover, induce S and G₂/M phase arrest in T lymphocytes.