Intra-articular injection of the selective cyclooxygenase-2 inhibitor meloxicam (Mobic) reduces experimental osteoarthritis and nociception in rats.

OBJECTIVE: To study the effect of intra-articular injection of meloxicam (Mobic) on the development of osteoarthritis (OA) in rats and examine concomitant changes in nociceptive behavior and the expression of mitogen-activated protein kinases (MAPKs) in articular cartilage chondrocytes. METHODS: OA was induced in Wistar rats by right anterior cruciate ligament transection (ACLT); the left knee was not treated. The OA + meloxicam (1.0 mg) group was injected intra-articularly in the ACLT knee with 1.0 mg of meloxicam once a week for 5 consecutive weeks starting 5 weeks after ACLT. The OA + meloxicam (0.25 mg) group was treated similarly with 0.25 mg meloxicam. The sham group underwent arthrotomy only and received vehicle of 0.1 mL sterile 0.9% saline injections, whereas the naive rats in meloxicam-only groups were treated similarly with 1.0- and 0.25-mg meloxicam. Nociception was measured as secondary mechanical allodynia and hind paw weight-bearing distribution at before (pre-) and 5, 10, 15, and 20 weeks post-ACLT. Histopathology of the cartilage and synovia was examined 20 weeks after ACLT. Immunohistochemical analysis was performed to examine the effect of meloxicam on MAPKs (p38, c-Jun N-terminal kinase (JNK), and extracellular signal-regulated kinase (ERK)) expression in the articular cartilage chondrocytes. RESULTS: OA rats receiving intra-articular meloxicam treatment showed significantly less cartilage degeneration and synovitis than saline-treated controls. Nociception were improved in the OA + meloxicam groups compared with the OA group. Moreover, meloxicam attenuated p38 and JNK but enhanced ERK expression in OA-affected cartilage. CONCLUSIONS: Intra-articular injection of meloxicam (1) attenuates the development of OA, (2) concomitantly reduces nociception, and (3) modulates chondrocyte metabolism, possibly through inhibition of cellular p38 and JNK, but enhances ERK expression.

T cell genetic background determines default T helper phenotype development in vitro.

A host's ability to resist certain pathogens such as Leishmania major can depend upon the phenotype of T helper (Th) subset that develops. Different murine genetic backgrounds are known to significantly alter the direction of Th subset development, although the cellular basis of this influence is poorly understood. To examine the basis of this effect we used an in vitro alpha/beta-T cell receptor (TCR) transgenic system for analysis of Th phenotype development. To control for TCR usage, we derived the DO11.10 alpha/beta-TCR transgene in several genetic backgrounds. Our findings suggest that the effects of genetic background on Th phenotype development reside within the T cell, and not the antigen-presenting cell compartment. Transgenic T cells from both the B10.D2 and BALB/c backgrounds showed development toward either the Th1 or Th2 phenotype under the strong directing influence of interleukin (IL) 12 and IL4, respectively. However, when T cells were activated in vitro under neutral conditions in which exogenous cytokines were not added, B10.D2-derived T cells acquired a significantly stronger Th1 phenotype than T cells from the BALB/c background, correspondent with in vivo Th responses to Leishmania in these strains. Importantly, these cytokine differences resulted in distinct functional properties, because B10.D2- but not BALB/c-derived T cells could induce macrophage production of nitric oxide, an important antimicrobial factor. Thus, the genetically determined default Th phenotype development observed in vitro may correspond to in vivo Th subset responses for pathogens such as Leishmania which do not initiate strong Th phenotype-directing signals.

B7 and interleukin 12 cooperate for proliferation and interferon gamma production by mouse T helper clones that are unresponsive to B7 costimulation.

We have previously shown that dendritic cells isolated after overnight culture, which can express B7 and are potent stimulators of naive T cell proliferation, are relatively poor at inducing the proliferation of a panel of murine T helper 1 (Th1) clones. Maximal stimulation of Th1 clones was achieved using unseparated splenic antigen presenting cells (APC). An explanation for these findings is provided in the present study where we show that FcR+ L cells transfected with B7 stimulate minimal proliferation of Th1 clones in response to anti-CD3 antibodies, in contrast to induction of significant proliferation of naive T cells. However, addition of interleukin 12 (IL-12) to cultures of Th1 cells stimulated with anti-CD3 and FcR+ B7 transfectants resulted in a very pronounced increase in proliferation and interferon gamma (IFN-gamma) production. Exogenous IL-12 did not affect the B7-induced proliferation of naive T cells. This showed that whereas costimulatory signals delivered via B7-CD28 interaction are sufficient to induce significant proliferation of naive T cells activated through occupancy of the T cell receptor, Th1 T cell clones require cooperative costimulation by B7 and IL-12. This costimulation was shown to be specific by inhibition of proliferation and IFN-gamma production using chimeric soluble cytolytic T lymphocyte-associated antigen 4-human IgG1Fc (CTLA4-Ig) and anti-IL-12 antibodies. Furthermore, the significant antigen specific proliferation and IFN-gamma production by Th1 clones observed when splenocytes were used as APC was almost completely abrogated using CTLA4-Ig and anti-IL-12 antibodies. Thus two costimulatory signals, B7 and IL-12, account for the ability of splenic APC to induce maximal stimulation of Th1 clones. IL-10 downregulates the expression of IL-12 by IFN-gamma-stimulated macrophages and this may account largely for t the ability of IL-10 to inhibit APC function of splenic and macrophage APC for the induction of Th1 cell proliferation and IFN-gamma production. Indeed we show that IL-12 can overcome the inhibitory effect of IL-10 for the APC-dependent induction of proliferation and IFN-gamma production by Th1 clones. These results suggest that proliferation by terminally differentiated Th1 clones, in contrast to naive T cells, requires stimulation via membrane-bound B7 and a cytokine, IL-12. It is possible that these signals may result in the activation of unresponsive T cells during an inflammatory response. IL-10, by its role in regulating such innate inflammatory responses, may thus help to maintain these T cells in an unresponsive state.

Glucosamine sulfate reduces experimental osteoarthritis and nociception in rats: association with changes of mitogen-activated protein kinase in chondrocytes.

OBJECTIVE: To study the effects of oral glucosamine sulfate on the development of osteoarthritis (OA) and to examine concomitant changes in the nociceptive behavior of rats. METHODS: OA was induced in Wistar rats by anterior cruciate ligament transection (ACLT) of the right knee; the left knee was untreated. The OA+glucosamine group received oral glucosamine sulfate (250 mg/kg/day) in a 2-g wafer once a day for 10 consecutive weeks starting at week 5 after ACLT. The OA group was treated as above with 2-g wafers (placebo). The control group of naïve rats received 2-g wafers only. The glucosamine alone group comprised naïve rats receiving glucosamine sulfate only. Nociceptive behavior (mechanical allodynia and weight-bearing distribution of hind paws) during OA development was analyzed pre- and 3, 6, 9, 12, 15, and 18 weeks post-ACLT. Macroscopic and histologic studies were then performed on the cartilage and synovia. Immunohistochemical analysis was performed to examine the effect of glucosamine on expression of mitogen-activated protein kinases (MAPKs) in the articular cartilage chondrocytes. RESULTS: OA rats receiving glucosamine showed a significantly lower degree of cartilage degeneration than the rats receiving placebo. Glucosamine treatment also suppressed synovitis. Mechanical allodynia and weight-bearing distribution studies showed significant improvement in the OA+glucosamine group as compared to the OA group. Moreover, glucosamine attenuated p38 and c-Jun N-terminal kinase (JNK) but increased extracellular signal-regulated kinase 1/2 (ERK) expression in OA-affected cartilage. CONCLUSION: Our results indicate that treatment with oral glucosamine sulfate in a rat OA model (1) attenuates the development of OA, (2) concomitantly reduces nociception, and (3) modulates chondrocyte metabolism, possibly through inhibition of cell p38 and JNK and increase of ERK expression.

Electro-optic guided-to-radiation mode conversion in annealed proton-exchanged PPLN waveguides.

We report the design and experimental demonstration of electro-optically active TM-guided to TE-radiation mode converters in annealed proton-exchanged (APE) periodically poled lithium niobate (PPLN) channel waveguides in telecom S-C-L bands (1495-1640 nm). A maximum mode conversion efficiency of >95%/cm was obtained at 1520 nm from a 24-µm-period APE PPLN waveguide under an electro-optic (EO) field of ~6.3 V/µm at 35°C. This efficiency has been enhanced by a factor of >4.6 over a waveguide built in the single-domain (unpoled) LiNbO3; it is also to the best of our knowledge the most efficient guided-to-radiation (GTR) mode converter ever reported based on LiNbO3 on-axis waveguides. A conversion bandwidth of ~250 nm was also observed from this EO GTR mode converter.

Intra-articular magnesium sulfate (MgSO4) reduces experimental osteoarthritis and nociception: association with attenuation of N-methyl-D-aspartate (NMDA) receptor subunit 1 phosphorylation and apoptosis in rat chondrocytes.

OBJECTIVE: To study the effects of intra-articular injection of magnesium sulfate (MgSO(4)) on the development of osteoarthritis (OA) and to examine concomitant changes in the nociceptive behavior of rats. METHODS: OA was induced in Wistar rats with intra-articular injection of collagenase (500 U) in the right knee; the left knee was left untreated. In the OA+MgSO(4) group (n=7), the treated knee was injected with 500-microg (0.1-ml) MgSO(4) twice a week for 5 consecutive weeks starting at 1 week after collagenase injection; in the OA group (n=7), the same knee was injected with the same amount of physiological normal saline. In the MgSO(4) group (n=6), naïve rats received only MgSO(4) injections; in the control group (n=6), naïve rats received only physiological normal saline injections. Nociceptive behavior (mechanical allodynia and thermal hyperalgesia) on OA development was measured before and at 1, 2, 4, 6, and 8 weeks after collagenase injection, following which the animals were sacrificed. Gross morphology and histopathology were examined in the femoral condyles, tibial plateau, and synovia. Immunohistochemical analysis was performed to examine the effect of MgSO(4) on N-methyl-D-aspartate (NMDA) receptor subunit 1 phosphorylation (p-NR1) and apoptosis in the articular cartilage chondrocytes. RESULTS: OA rats receiving intra-articular MgSO(4) injections showed a significantly lower degree of cartilage degeneration than the rats receiving saline injections. MgSO(4) treatment also suppressed synovitis. Mechanical allodynia and thermal hyperalgesia showed significant improvement in the OA+MgSO(4) group as compared to the OA group. Moreover, MgSO(4) attenuated p-NR1 and chondrocyte apoptosis in OA-affected cartilage. CONCLUSIONS: Our results indicate that local intra-articular administration of MgSO(4) following collagenase injection in an experimental rat OA model (1) modulates chondrocyte metabolism through inhibition of cell NMDA receptor phosphorylation and apoptosis, (2) attenuates the development of OA, and (3) concomitantly reduces nociception.

Development of TH1 CD4+ T cells through IL-12 produced by Listeria-induced macrophages.

Development of the appropriate CD4+ T helper (TH) subset during an immune response is important for disease resolution. With the use of naïve, ovalbumin-specific alpha beta T cell receptor transgenic T cell, it was found that heat-killed Listeria monocytogenes induced TH1 development in vitro through macrophage production of interleukin-12 (IL-12). Moreover, inhibition of macrophage production of IL-12 may explain the ability of IL-10 to suppress TH1 development. Murine immune responses to L. monocytogenes in vivo are of the appropriate TH1 phenotype. Therefore, this regulatory pathway may have evolved to enable innate immune cells, through interactions with microbial pathogens, to direct development of specific immunity toward the appropriate TH phenotype.

Genetic susceptibility to Leishmania: IL-12 responsiveness in TH1 cell development.

The genetic background of T lymphocytes influences development of the T helper (TH) phenotype, resulting in either resistance or susceptibility of certain mouse strains to pathogens such as Leishmania major. With an in vitro model system, a difference in maintenance of responsiveness of T cells to interleukin-12 (IL-12) was detected between BALB/c and B10.D2 mice. Although naive T cells from both strains initially responded to IL-12, BALB/c T cells lost IL-12 responsiveness after stimulation with antigen in vitro, even when cocultured with B10.D2 T cells. Thus, susceptibility of BALB/c mice to infection with L. major may derive from the loss of the ability to generate IL-12-induced TH1 responses rather than from an IL-4-induced TH2 response.

Antigen-specific regulatory T-cell responses to intestinal microbiota.

The mammalian gastrointestinal tract can harbor both beneficial commensal bacteria important for host health, but also pathogenic bacteria capable of intestinal damage. It is therefore important that the host immune system mount the appropriate immune response to these divergent groups of bacteria-promoting tolerance in response to commensal bacteria and sterilizing immunity in response to pathogenic bacteria. Failure to induce tolerance to commensal bacteria may underlie immune-mediated diseases such as human inflammatory bowel disease. At homeostasis, regulatory T (Treg) cells are a key component of the tolerogenic response by adaptive immunity. This review examines the mechanisms by which intestinal bacteria influence colonic T-cells and B-cell immunoglobulin A (IgA) induction, with an emphasis on Treg cells and the role of antigen-specificity in these processes. In addition to discussing key primary literature, this review highlights current controversies and important future directions.

The role of TCR specificity in naturally arising CD25+ CD4+ regulatory T cell biology.

CD25+ CD4+ T cells (TR) are a naturally arising subset of regulatory T cells important for the preservation of self-tolerance and the prevention of autoimmunity. Although there is substantial data that TCR specificity is important for TR development and function, relatively little is known about the antigen specificity of naturally arising TR. Here, we will review the available evidence regarding naturally arising TR TCR specificity in the context of TR development, function, and homeostasis.

Endoscopic sympathectomy treatment for craniofacial hyperhidrosis.

OBJECTIVE: To present endoscopic T-2 sympathectomy as a minimally invasive therapy for craniofacial hyperhidrosis (CH). DESIGN: Follow-up study of 30 patients with CH treated by the new method in a 4-year period. The duration of follow-up was from 8 to 44 months (mean, 15 months). SETTING: University hospital. PATIENTS: Thirty consecutive patients with CH (18 men, 12 women) treated by the new method. All patients were essentially in good health except that they suffered from distressing CH to the extent that their daily activities were often disturbed. Their ages ranged from 7 to 63 years (mean age, 42.8 years). INTERVENTION: Endoscopic sympathectomy on both sides was carried out in a 1-stage operation for all patients. MAIN OUTCOME MEASURES: The patients were interviewed 1 week and then 3 months after surgery and then followed up by telephone interview about the alleviation or recurrence of CH and complications. RESULTS: All of the treated patients obtained a satisfactory alleviation of CH. One case was complicated by a mild and transient ptosis of the left eye. No recurrence of CH was noticed during the follow-up period. CONCLUSIONS: This therapeutic procedure is minimally invasive and effective. It causes minimal discomfort and was associated with no major complications in this series. The patients require only an overnight hospital stay and the operation scars are small. Endoscopic sympathectomy has proven to be an effective method in treating patients with distressing CH.

Juvenile fibromatosis of the posterior mediastinum with intraspinal extension.

Chest radiography, CT, and MR imaging were performed in a 3-year-old girl who had posterior mediastinal fibromatosis with transforaminal intraspinal and chest wall extension. Chest radiographs and CT scans showed a slow-growing, noncalcified but locally aggressive left paravertebral mass. The mass was slightly hyperintense relative to muscle on both T1-weighted and fast spin-echo T2-weighted MR images.

Epidermolysis bullosa letalis with pyloric atresia in an infant.

Epidermolysis bullosa (EB) is a group of inherited diseases, that are characterized by vesiculobullous lesions that arise in response to minimal trauma or friction. The three major groups of EB differ according to the ultrastructural level of cleavage namely: simplex (epidermolytic), junctional and dystrophic (dermolytic). The combination of EB and pyloric atresia in rare and there is a definite association between them. We report a baby boy who died epidermolysis bullosa complications despite successful surgical correction of this pyloric atresia.

Minimally invasive surgery: video endoscopic thoracic sympathectomy for palmar hyperhidrosis.

Palmar hyperhidrosis (PH) is a common disorder in Taiwan. It often causes social embarrassment and occupational handicaps. So far, there has been no satisfactory treatment for PH. In 1990, we first developed a minimally invasive technique: video endoscopic sympathectomy to treat PH. The procedure has subsequently proven to be a standard treatment for PH. In this study, a survey of 9988 cases of PH patients from 17 hospitals in Taiwan treated by this method during the past 5 years is presented. Although there were some variations in the model of anaesthesia, technique and extent of sympathectomy, the postoperative results were generally satisfactory. Both sides of sympathectomy were mostly accomplished within half an hour in one stage. The operative scars were tiny and concealed in the axillary region. The patients were discharged from the hospital after an overnight stay. Complications such as pneumothorax, haemothorax (0.3%) or Horner's syndrome (0.1%) were rare. There was no surgical mortality in this series. The most common complication was compensatory hyperhidrosis which was usually mild to moderate and tolerable after reassurance. The recurrence rate of PH was approximately 1% in the first year and less than 3% during the 3 years of follow up. Intraoperative monitoring of palmar skin temperature (PST) was advocated to confirm an adequate sympathectomy warranting a definite result. En bloc ablation of T2 segment invariably resulted in a rise of PST to about 2 degrees C and was considered as an adequate extent of sympathectomy for PH. The refined technique was extended to treat young children with PH and patients with craniofacial hyperhidrosis. The therapeutic results were generally excellent with minimal morbidity and rare recurrence. It is concluded that video endoscopic en bloc T2 sympathectomy is a simple, minimally invasive and effective treatment for both adults and children with PH and also for patients with craniofacial hyperhidrosis.

Integration of CNS survival and differentiation by HIF2α.

Hypoxia-inducible factor (HIF) 1α and HIF2α and the inhibitor of apoptosis survivin represent prominent markers of many human cancers. They are also widely expressed in various embryonic tissues, including the central nervous system; however, little is known about their functions in embryos. Here, we show that zebrafish HIF2α protects neural progenitor cells and neural differentiation processes by upregulating the survivin orthologues birc5a and birc5b during embryogenesis. Morpholino-mediated knockdown of hif2α reduced the transcription of birc5a and birc5b, induced p53-independent apoptosis and abrogated neural cell differentiation. Depletion of birc5a and birc5b recaptured the neural development defects that were observed in the hif2α morphants. The phenotypes induced by HIF2α depletion were largely rescued by ectopic birc5a and birc5b mRNAs, indicating that Birc5a and Birc5b act downstream of HIF2α. Chromatin immunoprecipitation assay revealed that HIF2α binds to birc5a and birc5b promoters directly to modulate their transcriptions. Knockdown of hif2α, birc5a or birc5b reduced the expression of the cdk inhibitors p27/cdkn1b and p57/cdkn1c and increased ccnd1/cyclin D1 transcription in the surviving neural progenitor cells. The reduction in elavl3/HuC expression and enhanced pcna, nestin, ascl1b and sox3 expression indicate that the surviving neural progenitor cells in hif2α morphants maintain a high proliferation rate without terminally differentiating. We propose that a subset of developmental defects attributed to HIF2α depletion is due in part to the loss of survivin activity.

Mechanisms of lysis by cytotoxic T lymphocyte clones. Lytic activity and gene expression in cloned antigen-specific CD4+ and CD8+ T lymphocytes.

Cloned murine Th having properties of either Th1 or Th2 cells as well as CD8+ CTL were tested for the capacity to lyse: 1) nucleated target cells bearing Ag or coated with anti-CD3 mAb, or 2) SRBC target cells coated with anti-CD3 mAb in a short term 51Cr-release assay. The lysis of SRBC occurs by a mechanism that does not involve nuclear degradation but presumably does involve membrane damage. Three patterns were observed: CTL and some Th2 cells lysed efficiently nucleated target cells and SRBC coated with anti-CD3 mAb. Th1 and some Th2 T cells lysed nucleated target cells but did not lyse efficiently the SRBC coated with anti-CD3 mAb. Finally, some Th2 cells failed to lyse efficiently either nucleated or SRBC targets. We also examined these clones for their expression of N-alpha-benzyloxycarbonyl-L-lysin thiobenzyl esterase activity, and for the expression of perforin or CTLA-1 (granzyme B) mRNA. Total N-alpha-benzyloxycarbonyl-L-lysin thiobenzyl esterase activity expressed by CTL and Th2 clones tended to be higher than that of Th1 cells. Perforin mRNA and CTLA-1 mRNA were readily detectable in CTL and some Th2 clones. Expression of perforin and CLTA-1 mRNA correlated well with the capacity of these clones to lyse SRBC coated with anti-CD3 mAb. Our results show that some but not all Th2 clones have lytic characteristics similar to those of CD8+ CTL. Two mechanisms appear to contribute to their lytic process, one mechanism of lysis involves membrane damage that correlates with the expression of perforin mRNA; a second mechanism involves the induction of DNA degradation in the target cells. In contrast, some CD4+ effector cells appear to lack the capacity to lyse efficiently via the mechanism involving membrane damage and may only have the lytic activity associated with the capacity to induce DNA degradation.

Infantile hypertrophic pyloric stenosis presenting as pseudo-Bartter's syndrome and seizures: report of one case.

We report a hypertrophic pyloric stenosis case with an unusual initial presentation of seizures and Bartter's syndrome like symptoms. This case suffered from vomiting, diarrhea and poor appetite for several days, and seizures developed after these symptoms. From laboratory tests, hypochloremic and hypokalemic metabolic alkalosis associated with hyperreninemia, hyperaldosteronism and normal blood pressure were noted. Pseudo-Bartter's syndrome was diagnosed through these clinical and laboratory tests. Although the first abdominal echo was negative, we still speculated about the peculiar symptoms of vomiting and it's relationship to pseudo-Bartter's syndrome. After all, we found the hypertrophic pyloric stenosis through an upper gastrointestinal series. From these experiences, we postulated that it's very important to put the hypertrophic pyloric stenosis into the differential diagnosis of pseudo-Batter's syndrome.

Pathogen-induced Th1 phenotype development in CD4+ alpha beta-TCR transgenic T cells is macrophage dependent.

We used an ovalbumin (OVA)-specific alpha beta-TCR transgenic mouse system to examine the cellular basis of CD4+ T helper (Th) phenotype development in vitro. Heat-killed Listeria monocytogenes (HKLM) strongly promotes the in vitro development of a Th1 phenotype in OVA-specific transgenic T cells. Listeria monocytogenes effects to promote the Th1 phenotype are antigen presenting cell (APC) dependent and occur when splenic APCs, but not the B cell hybridoma TA3, are present during T cell activation. However, addition of FACS-sorted macrophages to TA3 activated cultures restores the ability of Listeria to induce Th1 development. This effect on T cell development does not require MHC-restricted antigen presentation by macrophages, but may act through soluble factors. Although the presence of interferon gamma is necessary for Listeria induction of Th1 development, IFN-gamma alone is insufficient to induce Th1 development. Furthermore, Listeria induction of the Th1 phenotype does not require several known products of activated macrophages, including interleukin-1 (IL-1), tumor necrosis factor (TNF-alpha), IL-6, or nitric oxide. Although transforming growth factor-beta (TGF-beta) may mediate some Listeria effects, it does not fully reconstitute Listeria effects to promote Th1 development. In summary, host interactions with bacterial pathogens can affect the development of specific Th subsets, allowing innate immune cells to direct development of specific immune phenotype. For Listeria monocytogenes, the induction of the Th1 phenotype may involve a novel cytokine distinct from several known factors produced by activated macrophages.

Dendritic cells and macrophages are required for Th1 development of CD4+ T cells from alpha beta TCR transgenic mice: IL-12 substitution for macrophages to stimulate IFN-gamma production is IFN-gamma-dependent.

We have examined the antigen presenting cell (APC) requirements for primary T cell activation and T helper (Th) cell phenotype differentiation using naive CD4+ T cells from alpha beta TCR transgenic mice. Purified dendritic cells were the principal cell required for induction of primary ovalbumin peptide specific T cell activation and clonal expansion. However, dendritic cells did not induce differentiation of T cells toward Th1 or Th2 phenotype. Addition of IL-4 during primary dendritic cell stimulations of T cells resulted in the development of a Th2 phenotype which produced high levels of IL-4 during secondary and tertiary stimulation. In contrast, development of Th1 cells producing high levels of IFN-gamma could not be induced with dendritic cells alone but required the addition of appropriately activated macrophages. Addition of splenic or peritoneal B cells did not induce Th1 development. Activated splenic macrophages induced Th1 development via a non-MHC restricted mechanism. Thus, requirements for induction of proliferation of naive CD4+ T cells are distinct from those directing Th1 phenotype development. IL-12 could replace the requirement for macrophages to induce Th1 development when T cells were activated with dendritic cells. Furthermore, this IL-12 mediated development of Th1 cells producing high levels of IFN-gamma was dependent on IFN-gamma.

Separation of CD4+ functional responses by peptide dose in Th1 and Th2 subsets expressing the same transgenic antigen receptor.

CD4+ T cells from alpha beta-TCR transgenic mice were used to explore the effect of antigen dose on various functional activities. This transgenic system provides for a source of antigen-specific T cells with the same TCR which can develop into Th1 and Th2 phenotypes under controlled conditions. Of particular interest was to determine if detachment of adherent targets from their substrate could be separated from other functional activities by either antigen dose or functional subset. Using this model, we have found that (a) Th1 and Th2 phenotypes exhibit a similar peptide dose-dependent pattern of detachment and lysis, although Th2 are generally less lytic on both fibroblast and lymphoma targets; (b) detachment and lysis can be dissociated from cytokine production by low peptide doses; (c) detachment and lysis can be physiologically as well as temporally and pharmacologically uncoupled as most targets recovered after detachment by Th2 effectors retain their capacity to proliferate.