Kinetics of Th17‐related cytokine expression in experimentally induced rat periapical lesions

Th17‐related cytokines are essential factors in various pathological states, including inflammatory bone destruction. This study investigated the contribution of Th17‐related cytokines to the progress of experimentally induced rat periapical lesions. Periapical pathoses were induced by unsealed exposure of the pulp chamber of the lower first molars. A variety of immunocompetent cells, including CD68⁺ macrophages, Ia antigen⁺ cells and TCRαβ⁺ T cells, were observed in the lesions. The expression levels of Th17‐related cytokines, IL‐17 and IL‐23, and of pro‐inflammatory cytokines, IL‐1β and IL‐6, were significantly increased at 14 days (expansion stage) compared with normal periapical tissues. The expression levels of Foxp3, a regulatory T cell (Treg)‐related gene, and of IL‐10, an anti‐inflammatory cytokine, were higher at 28 days (chronic stage) than at 14 days. These findings suggest that Th17‐related cytokines may be primary contributors to the initiation of periapical bone destruction, and that lesion expansion may be regulated by anti‐inflammatory mediators.     

辅助性T17细胞在牙周炎小鼠中的免疫状态研究

目的 研究辅助性T（Th）17细胞在牙周炎小鼠中的免疫状态。方法 将7周龄C57BL/6雌性小鼠随机分为牙周炎组和对照组,每组4只。牙周炎组采用口腔涂抹牙龈卟啉单胞菌（P. gingivalis）的方法建立牙周炎动物模型。对照组涂抹PBS液。在涂抹结束后的第4周取材,流式细胞仪检测CD4+维甲酸相关核孤儿受体（ROR）γτ+（Th17）细胞;酶联免疫吸附（ELISA）检测Th17细胞相关的细胞因子白细胞介素（IL）-17A的蛋白表达。结果 牙周炎小鼠牙龈组织、颈部淋巴结和外周血中CD4+ RORγτ+（Th17）细胞在总CD4+ T细胞中的比例和细胞数量显著高于对照组（P<0.01）。与对照组相比,牙周炎组IL-17A的表达增加（P<0.05）。结论 在牙周炎的发生发展中,Th17细胞介导的细胞免疫应答增强,牙龈组织、颈部淋巴结和外周血可能是Th17细胞介导免疫应答的主要场所。     

Porphyromonas gingivalis infection enhances Th17 responses for development of atherosclerosis

Objectives

Porphyromonas gingivalis has been shown to associate with the development of atherosclerosis. Recent studies indicate that IL-17-producing T helper 17 (Th17) cells have been correlated with the emergence of atherosclerosis. Therefore, we investigated whether the Th17 cell response and expression of Th17-related molecules, in contrast with Th1- and Treg cells, are enhanced by P. gingivalis-challenge in Apolipoprotein E knockout (ApoE KO) mice.

Design

Five mice were intravenously injected with P. gingivalis three times a week for 3 weeks and killed at 15 weeks of age. The proximal aorta lesion area, flow cytometry analysis and IL-17, IL-10, IFN-γ, and IL-1β levels in splenic cultures, and expression of Th17-related molecules in spleen and hearts were examined.

Results

P. gingivalis-challenge showed notable accumulation of atherosclerotic plaques by Oil Red O-staining in ApoE KO mice. Intracellular cytokine staining revealed that significantly elevated CD4⁺ interleukin (IL)-17A⁺ T cells and slightly increased CD4⁺ Foxp3⁺ T cells was recognized in spleen cells of P. gingivalis-challenged mice compared with those from non-infected mice. P. gingivalis-challenge significantly increased IL-17 and IL-1β production and RORγt expression in splenic cells. Furthermore, the expression of Th17-related genes such as IL-6, TGF-β, RORγt and STAT3 were elevated in splenic cells as well as heart tissue of P. gingivalis-challenged mice.

Conclusion

These results suggest that P. gingivalis infection may enhance pro-inflammatory Th17 cell responses in lesion areas and spleen, thereby accelerating atherosclerosis.     

Role of distinct CD4+ T helper subset in pathogenesis of oral lichen planus

Oral lichen planus (OLP) is one of the most common chronic inflammatory oral mucosal diseases with T‐cell‐mediated immune pathogenesis. In subepithelial and lamina propria of OLP local lesions, the presence of CD4⁺ T helper (CD4⁺ Th) cells appeared as the major lymphocytes. These CD4⁺ T lymphocytes can differentiate into distinct Th cell types such as Th1, Th2, Treg, Th17, Th22, Th9, and Tfh within the context of certain cytokines environment. Growing evidence indicated that Th1/Th2 imbalance may greatly participate into the cytokine network of OLP immunopathology. In addition, Th1/Th2 imbalance can be regulated by the Treg subset and also greatly influenced by the emerging novel CD4⁺ Th subset Th17. Furthermore, the presence of novel subsets Th22, Th9 and Tfh in OLP patients is yet to be clarified. All these Th subsets and their specific cytokines may play a critical role in determining the character, extent and duration of immune responses in OLP pathogenesis. Therefore, we review the roles of distinct CD4⁺ Th subsets and their signature cytokines in determining disease severity and susceptibility of OLP and also reveal the novel therapeutic strategies based on T lymphocytes subsets in OLP treatment.     

Identification of T‐cell epitopes of Porphyromonas gingivalis heat‐shock‐protein 60 in periodontitis

The heat shock proteins (hsp) of bacterial species are considered to be involved in regulating the autoimmune mechanism in human diseases due to the considerable homology of their sequences with human hsp. To elucidate how stress proteins contribute to the immunopathogenesis of periodontitis, mononuclear cells from gingival connective tissue of 10 periodontitis patients were simulated with Porphyromonas gingivalis hsp60. T‐cell lines reactive to P. gingivalis hsp60 were established from each patient to define T‐cell epitope specificities. Anti‐P. gingivalis IgG antibody titres were elevated in all patients. We could establish P. gingivalis hsp‐reactive T‐cell lines from gingival mononuclear cells that were mixtures of CD4⁺ and CD8⁺ cells. Of 108 overlapping synthetic peptides spanning the whole P. gingivalis hsp60 molecule, 10 peptides with epitope specificities for T‐cells were identified, and were identical to those reported be B‐cell epitopes in periodontitis.     

Oral immunization with Porphyromonas gingivalis outer membrane protein and CpG oligodeoxynucleotides elicits T helper 1 and 2 cytokines for enhanced protective immunity

The aim of this study was to evaluate the efficacy of an oral vaccine containing the 40‐kDa outer membrane protein of Porphyromonas gingivalis (40K‐OMP) and synthetic oligodeoxynucleotides containing unmethylated CpG dinucleotides (CpG ODN) to control oral infection by P. gingivalis. Oral immunization with 40K‐OMP plus CpG ODN induced significant 40K‐OMP‐specific serum immunoglobulin G (IgG), IgA, and saliva IgA antibody responses. The 40K‐OMP‐specific CD4⁺ T cells induced by oral 40K‐OMP plus CpG ODN produced both T helper type 1 (Th1; interferon‐γ) and Th2 (interleukin‐4) cytokines. Furthermore, increased frequencies of CD11c⁺ B220⁺ dendritic cells (DCs) and CD11c⁺ CD11b⁺ DCs with upregulated expression of CD80, CD86, CD40, and major histocompatibility complex class II molecules were noted in spleen, Peyer’s patches, and cervical lymph nodes. Immunized mice were then infected orally with P. gingivalis to determine whether the immune responses induced by oral 40K‐OMP plus CpG ODN were capable of suppressing the bone resorption caused by P. gingivalis infection. Mice given 40K‐OMP plus CpG ODN showed significantly reduced bone loss associated with oral infection by P. gingivalis. Oral administration of 40K‐OMP together with CpG ODN induces Th1‐type and Th2‐type cells, which provide help for protective immunity against P. gingivalis infection. This may be an important tool for the prevention of chronic periodontitis.     

Porphyromonas gingivalis antigen preferentially stimulates T cells to express IL‐17 but not receptor activator of NF‐κB ligand in vitro

Although T cells have been implicated in the pathogenesis and are considered to be central to both their progression and control of chronic inflammatory periodontal diseases, the precise contribution of T cells to tissue destruction has not been fully clarified. Recently, interleukin (IL)‐17 and receptor activator of Nuclear factor κB NF‐κB ligand (RANKL) have received much attention as a result of their proinflammatory and bone metabolic roles, respectively. We therefore investigated the effect of outer membrane protein (OMP) from Porphyromonas gingivalis (P. gingivalis) on the expression of IL‐17 and RANKL in peripheral blood mononuclear cells (PBMCs) and compared these between gingivitis and periodontitis, which are representative of stable and progressive lesions, respectively. The in situ expression of these molecules was also examined. P. gingivalis OMP stimulated PBMCs to express IL‐17 at both the mRNA and protein level. Although the mean expression of mRNA was not different between the two groups, the mean level of IL‐17 in the culture supernatants was higher in gingivitis patients than in periodontitis patients. However, the frequency of IL‐17‐positive samples was higher in the periodontitis patients. This stimulatory effect was not evident for RANKL expression in either periodontitis or gingivitis patients. In gingival tissue samples, IL‐17 mRNA was detected in gingivitis more frequently than in periodontitis. The expression of RANKL mRNA was much lower than that of IL‐17 in terms of both level and frequency. These results suggest that IL‐17 but not RANKL may be involved in the pathogenesis of periodontal diseases. However, there may be negative regulatory mechanisms for IL‐17 in gingivitis.     

Serotype b of Aggregatibacter actinomycetemcomitans increases osteoclast and memory T‐lymphocyte activation

During periodontitis, alveolar bone resorption is associated with activation of T helper type 17 (Th17) lymphocytes and receptor activator of nuclear factor‐κB ligand (RANKL) ‐induced osteoclasts. We previously reported that serotype b of Aggregatibacter actinomycetemcomitans has a higher capacity to trigger Th17‐type differentiation and function in activated T lymphocytes and its lipopolysaccharide is a more potent immunogen compared with the other serotypes. This study aimed to investigate whether serotype b of A. actinomycetemcomitans induces higher Th17‐associated RANKL production, RANKL‐induced osteoclast activation, and antigen‐specific memory T lymphocyte proliferation. On naive CD4⁺ T lymphocytes stimulated with autologous dendritic cells primed with different A. actinomycetemcomitans serotypes, RANKL production, T‐bet, GATA‐3, RORC2 and Foxp3 expression, RORC2/RANKL intracellular double‐expression, TRAP⁺ osteoclast activation, and bone resorption were quantified. The frequency of proliferating memory T lymphocytes in response to A. actinomycetemcomitans serotypes was determined in periodontitis and healthy subjects. Naive CD4⁺ T lymphocytes stimulated by serotype b‐primed dendritic cells elicited higher levels of RANKL, RORC2, TRAP⁺ osteoclasts, and bone resorption than the same cells stimulated with the other serotypes. RANKL positively correlated and co‐expressed with RORC2. Memory T lymphocytes responding to serotype b were more frequently detected in periodontitis patients than healthy subjects. These results indicate that serotype b of A. actinomycetemcomitans is associated with higher production of RANKL and these increased levels are associated with Th17 lymphocyte induction, osteoclast activation, and bone resorption.     

Identification of gingipain‐specific I‐Ab‐restricted CD4+ T cells following mucosal colonization with Porphyromonas gingivalis in C57BL/6 mice

Chronic periodontitis is associated with Porphyromonas gingivalis infection. Although virulence factors of P. gingivalis are hypothesized to contribute to the pathogenesis of periodontitis, it is unclear whether the local CD4⁺ T‐cell‐mediated response they elicit prevents or contributes to periodontal bone destruction. We hypothesize that major histocompatibility complex class II I‐A^b‐binding peptides existing in Kgp and RgpA are presented to CD4⁺ T cells during P. gingivalis oral colonization. The protein sequences of gingipains RgpA and Kgp, and OMP40 and OMP41 of P. gingivalis were scanned using an I‐A^b‐binding matrix. From this analysis we identified 53 candidate peptides that had the potential to engage the peptide‐binding groove of the I‐A^b molecule of C57BL/6 mice. An ELISpot‐based screen revealed those peptide‐primed effector/memory CD4⁺ T cells that could be re‐stimulated in vitro with P. gingivalis or the peptide itself to produce interleukin‐17A or interferon‐γ. Two immunodominant peptides, Kgp_467–477 (pKgp) and RgpA_1054–1064/Kgp_1074–1084 (pR/Kgp) were identified and engineered to be displayed on I‐A^b molecular tetramers. Peptide pR/Kgp is conserved across all sequenced P. gingivalis strains. C57BL/6 mice were orally inoculated with P. gingivalis strain 53977 and cervical lymph node cells were stained with phycoerythrin‐conjugated pKgp::I‐A^b and pR/Kgp::I‐A^b tetramers. We found that only pR/Kgp::I‐A^b bound with the desired specificity to gingipain‐specific CD4⁺ T cells. The pR/Kgp::I‐A^b tetramer complex will allow the identification of effector/memory CD4⁺ T cells specific for two virulence factors of P. gingivalis strains associated with periodontal disease.     

Imbalance of Interleukin-17+ T-cell and Foxp3+ Regulatory T-cell Dynamics in Rat Periapical Lesions

Introduction

Interleukin (IL)-17⁺ T-helper (Th17) cells and Foxp3⁺ regulatory T (Treg) cells are CD4⁺ T-helper cells with reciprocal functions in immunology and bone metabolism. The present study aimed to investigate the expression dynamics of Th17 and Treg cells in rat periapical lesions as well as their correlation with bone resorption.

Methods

Experimental pulp exposures were made in the lower first molars of 28 Wistar rats to induce periapical lesions. Rats were killed on days 0, 7, 21, and 35. Mandibles were prepared for micro–computed tomography scanning, histologic observation, immunohistochemistry, enzyme histochemistry, and double immunofluorescence analysis.

Results

Through 3-dimensional and 2-dimensional measurements, the volume and area of periapical lesions visibly increased from day 7 to day 21 and then expanded slowly between days 21 and 35. IL-17–positive cells markedly increased from day 7 to day 35. However, Foxp3-positive cells remained at low levels until day 21 and then dramatically increased by day 35. The IL-17⁺/Foxp3⁺ ratio and number of osteoclasts simultaneously increased from day 7 to day 21 and then decreased on day 35. Finally, the distinct distribution of CD4⁺/IL-17⁺ Th17 and CD4⁺/Foxp3⁺ Treg cells was observed on days 7 and 35.

Conclusions

Our findings imply the imbalance of IL-17⁺ T cell and Foxp3⁺ Treg cell dynamics in induced periapical lesions, which may play an important role in periapical lesion progression.     

Role of Smoking and Type 2 Diabetes in the Immunobalance of Advanced Chronic Periodontitis

Background : This study evaluates the tissue levels of interleukin (IL)‐17⁺, IL‐15⁺, Foxp3⁺ cells, fibrosis, and plasma B‐cell infiltration in sites with chronic periodontitis in smokers and subjects with type 2 diabetes. Methods: Gingival biopsies were harvested from the following groups: systemically and periodontally healthy subjects (healthy group, n = 10); non‐smokers and subjects with advanced periodontitis and without diabetes (non‐risk factor/periodontitis group, n = 10); heavy smokers with advanced periodontitis and without diabetes (smoking/periodontitis group, ≥20 cigarettes per day for at least the past 5 years, n = 10); and non‐smoking poorly controlled subjects with diabetes (glycated hemoglobin levels ≥9%) with advanced periodontitis (diabetes mellitus/periodontitis group [DMP], n = 10). The number of IL‐17⁺, IL‐15⁺, and Foxp3⁺ cells was analyzed by immunohistochemistry, whereas the amount of fibrosis and plasma B‐cell infiltration in gingival tissue was analyzed by histomorphometry. Results: The number of Foxp3⁺ cells was significantly higher in the periodontitis groups compared to the healthy group (P <0.05). The DMP group presented higher levels of Foxp3⁺ cells than other periodontitis groups (P <0.05). The levels of IL‐15⁺ and IL‐17⁺ cells and the amount of fibrosis were higher in the DMP group than in the other groups (P <0.05). There was a trend for a decreased B‐cell infiltration in the DMP group (P >0.05). There was a slightly significant negative correlation between B‐cell infiltration and the amount of fibrosis (P <0.05). Conclusion: Upregulation of IL‐17⁺, IL‐15⁺, and Foxp3⁺ cells and increased amounts of fibrosis were observed in chronic periodontitis sites in subjects with type 2 diabetes, suggesting that periodontitis development in these subjects may be influenced by the T helper 17/T regulatory axis.     

Memory T cell subsets in healthy gingiva and periodontitis tissues

1 Background

In the gingival sulcus, effective and balanced innate and adaptive immune responses against subgingival plaque microbiome are crucial to maintain immune homeostasis. In this study, we investigated the memory T cell subsets in healthy gingiva and periodontitis tissues.

2 Methods

Anatomical localization of T cells (CD3⁺, CD4⁺, and CD8⁺) in healthy gingiva and periodontitis tissues were examined immunohistochemically. Subsets of memory T cells from isolated gingival cells were analyzed by flow cytometry using a cocktail of monoclonal antibodies (anti‐CD69, anti‐CD103, anti‐CD45RA, anti‐CCR7, anti‐CD28, and anti‐CD95). Intracellular cytokine staining of interleukin (IL)‐17 and interferon (IFN)‐γ expression on memory T cells in periodontitis tissues was also investigated.

3 Results

We found that healthy gingiva contains two memory T cell populations; a CD69^? recirculating population and a CD69⁺ gingiva‐resident memory T cell population. CD4⁺ T cells with transitional memory (T_TM) phenotype (CD45RA^?CCR7^?CD28⁺CD95⁺) constitute the major subset within these two populations. A significant increase in the proportion of CD4⁺CD69⁺CD103^? memory T cells was observed in periodontitis tissues compared with healthy gingiva. CD4⁺ memory T cells from periodontitis tissues produced either IL‐17 or IFN‐γ whereas CD8⁺ memory T cells produced only IFN‐γ.

4 Conclusions

Our findings suggest that recirculating and gingiva‐resident memory T cells could represent an important part of the immune surveillance network in the connective tissue, maintaining periodontal homeostasis. Imbalance of subgingival bacterial communities could damage gingival barrier allowing bacterial antigens to get access to the deeper connective tissue where they activate memory T cells leading to deleterious inflammation; a hallmark of periodontitis.     

Interleukin‐2, interleukin‐6 and T regulatory cells in peripheral blood of patients with Behçet’s disease and recurrent aphthous ulcerations

J Oral Pathol Med (2012) 41 : 73–79 Background: One of the factors involved in the pathogenesis of Behçet disease (BD) and recurrent aphthous ulcerations (RAU) is a cell‐mediated immune response in which several cytokines (interleukin‐2, interleukin‐6) and T regulatory cell (T reg cell) population seem to play a major role. The aim of this study was to measured the interleukin‐2 (IL‐2), interleukin‐6 (IL‐6) levels and analysis of CD4⁺ CD25⁺ Foxp‐3⁺ Treg cells in peripheral blood from patients with BD and RAU. In addition; we also analysed peripheral blood from healthy subjects for comparison. Methods: Thirty patients (15 men and 15 women) with BD, 30 patients (12 men and 18 women) with RAU and 15 healthy control subjects (nine men and six women) participated in the study. Analysis of CD4⁺ CD25⁺ Foxp‐3⁺ Treg cells, IL‐2 and IL‐6 levels have been measured in flow cytometry. Results: No statistical differences were observed in the serum levels of IL‐2 and IL‐6 between BD and RAU patients, and healthy subjects. Although there were no statistical differences in the number of CD4⁺ CD25⁺ Foxp‐3⁺ cells between groups, there were statistically significant differences in the number of CD4⁺ CD25^bright Treg cells. CD4⁺ CD25^bright Treg cells were significantly increased in BD and RAU patients compared to healthy subjects. Statistical analysis revealed no difference according to the number of CD4⁺ CD25^bright cells between BD and RAU patients. Conclusions: These results indicate that CD4⁺ CD25^bright T regulatory cells may be contributing factor in the pathogenesis of BD and RAU.     

Presence of Porphyromonas gingivalis and plasma cell dominance in gingival tissues with periodontitis

Oral Diseases (2010) 16 , 375–381 Objective: Porphyromonas gingivalis can invade and survive within its host epithelial cells. The aim of this study was to test our hypothesis that persistent presence of intracellular periodontal pathogens in gingival tissue causes the chronic inflammation and that an inappropriate immune response is a risk factor for periodontitis. Methods: Together with the presence of P. gingivalis, the distribution of B cells, plasma cells, and CD4⁺, CD8⁺, and FOXP3⁺ regulatory T cells was evaluated in gingival tissues from healthy (n = 7) and periodontitis (n = 8) sites by in situ hybridization and immunohistochemistry, respectively. Results: Porphyromonas gingivalis was detected in proximity to inflammatory infiltrates in three and seven biopsies from the healthy and periodontitis sites, respectively. Compared with healthy sites, periodontal lesions contained a significantly increased number of each immune cell studied with a relative dominance of plasma cells over T cells. Conclusions: Persistent bacterial invasion of gingival tissues in combination with a plasma cell‐dominant immune response may be involved in the pathogenesis of periodontitis.     

Identification of immunoreactive epitopes of the Porphyromonas gingivalis heat shock protein in periodontitis and atherosclerosis

Choi J, Lee S‐Y, Kim K, Choi B‐K. Identification of immunoreactive epitope of Porphyromonas gingivalis heat shock protein peptide in periodontitis and atherosclerosis. J Periodont Res 2011; 46: 240–245. © 2011 John Wiley & Sons A/S Background and Objective: Heat shock protein 60 (HSP60) of Porphyromonas gingivalis, a major periodontal pathogen, might be a trigger molecule linking infectious periodontitis and autoimmune atherosclerosis. The aim of this study was to identify the peptide specificity of anti‐P. gingivalis HSP60 monoclonal antibodies and their cross‐reactivity with bacterial and human HSPs. Their specific immunoreactivity to periodontal or atherosclerotic lesions was also investigated. Methods: Twenty patients with chronic periodontitis and 20 atherosclerosis patients who had undergone surgical intervention for atheromatous plaques with evidence of ongoing periodontal disease, were selected. Synthetic peptide 19 ((TLVVNRLRGSLKICAVKAPG)‐specific T‐cell lines were established from inflamed gingiva and atheromatous plaque and the phenotypes and cytokine profiles were characterized. Results: Thirty per cent of periodontitis patients and 100% of atherosclerosis patients reacted positively to cross‐reactive peptide 19 from both P. gingivalis and human HSP60. The peptide 19‐specific T‐cell lines demonstrated the phenotype characteristic of helper T cells (CD4⁺) but did not express CD25 or FOXP3. The interleukin‐10 levels were elevated significantly in the peptide 19 T‐cell line. Conclusion: Synthetic peptide 19 of P. gingivalis HSP60 is an immunoreactive epitope in the periodontitis–atherosclerosis axis.     

Aggressive and Chronic Periodontitis Correlate With Distinct Cellular Sources of Key Immunoregulatory Cytokines

Background: Chronic periodontitis (CP) and aggressive periodontitis (AP) are inflammatory diseases and the main cause of dental loss in adults. We aimed to investigate the expression of adhesion molecules and the source of proinflammatory and anti‐inflammatory cytokines in circulating mononuclear cells from patients with CP and AP. Methods: Peripheral blood mononuclear cells from healthy controls and CP or AP patients were collected. The expression of the cell adhesion molecules CD11a and CD11b, and the cellular sources of interleukin (IL)‐4, IL‐10, IL‐12, interferon‐γ, and tumor necrosis factor‐α by distinct subpopulations of circulating leukocytes were determined using flow cytometry. Results: The expression of CD11a, but not CD11b, was significantly higher within the CD4⁺ and CD8⁺ T cells in CP and AP than in healthy controls. The frequencies of tumor necrosis factor‐α–expressing CD4⁺ T cells and CD14⁺ cells were higher in AP and CP, compared to healthy controls, respectively. Moreover, the frequency of IL‐10 expressing CD14⁺ cells was higher in CP, but not AP, compared to healthy controls CD4⁺ T cells committed to IL‐4 production was higher in CP than in healthy controls. Conclusion: These results suggest the participation of CD11a in the pathogenesis of periodontal lesions and show distinct cellular sources of immunoregulatory cytokines in AP versus CP.     

Role of helper T cells in the humoral immune responses against 53‐kDa outer membrane protein from Porphyromonas gingivalis

Outer membrane protein with a 53‐kDa molecular weight (Ag53) isolated from Porphyromonas gingivalis evokes strong humoral immune responses in many periodontitis patients. To examine the effects of cytokines produced by Ag53‐specific Th cells on the IgG production against Ag53, we established Ag53‐specific Th‐cell lines from patients with early onset periodontitis and from healthy volunteers. We then developed a mixed lymphocyte culture system between Ag53‐specific Th cells and auto‐ or allo‐derived T‐cell‐depleted leukocytes produced from the subjects whose HLA class II haplotypes were completely matched. Interferon‐γ production was observed in all Th cell lines from patients and healthy subjects. As for Th2 type cytokines, interleukin (IL)‐4, IL‐5, IL‐6 and IL‐10 production varied greatly in Th cells regardless of the periodontal condition of the donor. Only Th cell lines with a high Th2/Th1 ratio induced Ag53‐specific IgG production when cocultured with T‐cell‐depleted leukocytes. Thus, the difference in Th2/Th1 balance may regulate the Ag53‐specific IgG production.