Comparative analysis of mononuclear cells isolated from mucosal lymphoid follicles of the human ileum and colon

Studies of human mucosal lymphoid follicles are rare and have been limited to children's Peyer's patches, which are visible at endoscopy. We investigated lymphoid follicles in ileum biopsies of 87 patients and surgical colon specimens from 66 cancer patients, and examined phenotype and function of isolated follicular immune cells. Two (0-10) and 12 (0-117) follicles per patient were found in ileum and colon samples respectively (P < 0.001). The number of lymphoid follicles mononuclear cells (LFMC) that could be isolated per patient was higher from colon compared with ileum specimens [725 000 (0-23 Mio) versus 100 000 (0-1.3 Mio), P < 0.001]. T cells were predominant in both LFMC and lamina propria mononuclear cells (LPMC), but B cells were more and plasma cells less frequent in LFMC. T cells from mucosal follicles were more frequently CD4-positive and CD62L-positive, but less frequently CD8-positive, CD103-positive and CD69-positive than lamina propria T cells. LFMC from ileum compared with colon showed no differences in mononuclear cell composition. Anti-CD3/CD28 stimulation induced similar proliferation of LFMC and LPMC from ileum and colon, as well as secretion of high levels of interferon-gamma, tumour necrosis factor-alpha and interleukin (IL)-2, but lower levels of IL-4, IL-6 and IL-10. LFMC from colon secreted more IL-2 than those from ileum. Our study shows that mucosal lymphoid follicles can be identified clearly in adult human colon and yield viable immune cells sufficient for phenotypical and functional analysis. The cellular composition of LFMC from ileum and colon is similar, and both secrete predominantly T helper type 1 cytokines.

Identification of the predominant antigenic epitopes in intestinal flora in IBD

The normal intestinal flora is required for the development of intestinal inflammation in animal models of inflammatory bowel disease (IBD). In humans, several studies indicated a potential association of Escherichia coli (E. coli) with IBD. In addition, we have shown that T-cell clones of IBD patients cross react toward different enteric bacterial species and thus likely respond to conserved bacterial antigens. Therefore, we hypothesized that highly conserved E. coli proteins might be a reasonable candidate to screen for abnormal T-cell responses in IBD. We used high-throughput techniques for cloning, expression, and purification under native conditions of a set of 271 conserved proteins of E. coli, of which 196 were used for whole blood stimulations to assess peripheral T helper (T(H))-cell responses. In addition, because of the association of an adherent-invasive E. coli with Crohn's disease (CD), we included 13 pathogenicity factors of E. coli in the study. We observed that pools of these conserved E. coli proteins less frequently induced interferon-gamma (IFNgamma) production in peripheral T(H) cells in patients with CD and ankylosing spondylitis (AS) compared with healthy controls. In addition, lower percentage of patients with CD and AS responded toward single proteins. The reason for the decreased frequency of an in vitro T(H)-cell IFNgamma response toward E. coli proteins in peripheral blood of CD and AS patients, e.g., increased suppression needs to be clarified.

Autochthonous hepatitis E virus infection in Germany with sequence similarities to other European isolates

Hepatitis E virus (HEV) is a common cause of acute hepatitis in endemic areas. Yet reports on autochthonous cases in other areas such as middle Europe are increasing. Here we report on a patient, who obviously acquired his HEV infection in Germany. Sequence analysis of the virus gained from his serum revealed homologies to other European isolates and swine isolates.

T regulatory cell suppression of colitis: the role of TGF-beta

Transforming growth factor β (TGF‐β) and interleukin 2 may be involved in IBD peripheral regulatory T cell pathophysiology, raising the possibility of therapeutic application of TGF‐β induced regulatory T cells in IBD patients

Safety and efficacy of intravenous pulse cyclophosphamide in acute steroid refractory inflammatory bowel disease

BACKGROUND AND AIMS

One major problem in the management of steroid refractory attacks of patients with inflammatory bowel disease (IBD) is the establishment of a rapidly acting immunosuppressive regimen. Based on its well known efficacy in systemic vasculitis, intravenous cyclophosphamide pulse therapy was used in refractory IBD patients to evaluate both its efficacy and safety.

METHODS

Between December 1998 and May 2001, seven patients (Crohn's disease, n=5; indeterminate colitis, n=1) with severe steroid refractory IBD (Crohn's disease activity index (CDAI) 264-479 points) received 4-6 cycles of monthly treatment with intravenous cyclophosphamide (750 mg) in a prospective uncontrolled pilot study.

RESULTS

All patients improved after two intravenous pulses of cyclophosphamide and six of seven patients achieved complete remission (CDAI <150 points). One patient with Crohn's disease of the small and large bowel showed an impressive clinical response but did not enter into remission. Tapering to low dose steroids was possible in all responders. Remission was maintained in all patients for 18 months (median) but required a second course of intravenous pulse cyclophosphamide in one patient. The drug was well tolerated except for two episodes of candida oesophagitis.

CONCLUSIONS

Intravenous pulse cyclophosphamide may be a safe and effective treatment in patients with severe IBD unresponsive to steroid treatment and merits evaluation in a controlled trial.

Conserved TCR beta chain usage in reactive arthritis; evidence for selection by a putative HLA-B27-associated autoantigen

Previous work suggested that expanded CD8+ T-cell clones in the synovial fluid (SF) of HLA-B27+ patients with reactive arthritis (ReA) preferentially use the T-cell receptor variable region (TCRBV) 1, similar CDR3 sequences, and joining region (BJ) 2S3. To determine the range of conservation and disease-specificity of CDR3-sequences, we analyzed the TCRBV1-J2S3 repertoire from 33 healthy HLA-B27+ individuals, patients with various types of spondyloarthropathies (SpA), and with rheumatoid arthritis (RA) by CDR3-spectratyping. After collection and database submission of all available TCRB-CDR3 from HLA-B27-restricted or SpA-derived T cells, we systematically screened the entire human sequence database for sequences similar to the B27/SpA-related CDR3. Spectratyping revealed expanded T cell clones using conserved TCRBV1J2S3 in the SF from 5/6 of the patients with acute ReA but not among the controls. In database searches, 50 HLA-B27 or SpA-related CDR3-sequences generated similar clusters of matched sequences, and matched reciprocally. Identical or closely related sequences were identified in 15 different individuals and a canonical ReA-associated TCRB was defined [BV1-CASSVG(V/I/L)(Y/F)STDTQYF-J2S3]. All but one patient-derived conserved sequences originated from acute stage ReA-patients, and were not present among approximately 3800 other human TCRB sequences in the database. Five of the conserved sequences originated from T cell clones that recognized uninfected cells in an HLA-B27-restricted fashion, implying a role of HLA-B27-restricted CD8+ T cells specific for a ubiquitous self- or cross-reactive microbial determinant in the early phase of ReA. Related sequences were independently identified in four different laboratories. The consensus TCRB motif could be a helpful diagnostic marker in HLA-B27-associated 'undifferentiated arthritis'.

Immune response to autologous and heterologous Helicobacter pylori antigens in humans

Infection of humans with Helicobacter pylori results in the development of chronic gastritis and plays an important role in gastric ulcer pathogenesis. Despite the infiltration of the mucosa with specific immunocompetent cells and production of specific antibodies, the infection usually persists for life. This study was performed to investigate if immunologic mechanisms exist which could contribute to the inability of the host to terminate the infection. Therefore, we compared the in vitro immunoreactivity of peripheral blood mononuclear cells (PBMC) from H. pylori-infected patients after stimulation with sonicated H. pylori bacteria from the stomach of the patient (autologous bacterial strain) with stimulation by bacteria from other patients (heterologous bacteria). We measured cell proliferation, expression of T cell activation markers CD25, HLA-DR, and CD71, as well as production ofinterleukin-10 (IL-10), an inhibitory cytokine. We found that the proliferative response of PBMC was significantly lower after autologous than after heterologous stimulation. Furthermore, secretion of IL-10 in the culture supernatants was significantly higher when PBMC were incubated with autologous than with heterologous H. pylori antigens. No significant differences between autologous or heterologous stimulation were observed in the increased expression of T cell activation markers. These data indicate that systemic immunologic response to H. pylori are strain-dependent. For further studies of the immune responses towards H. pylori, the use of an autologous stimulatory system seems necessary.

[Abdominal tuberculosis: a rare differential diagnosis of pancreatic carcinoma]

HISTORY AND ADMISSION FINDINGS

A 79-year-old local resident, presenting with abdominal pain, sweating and weight loss and suspected of having cancer of the pancreas was referred for diagnosis and treatment. Physical examination was negative except for pain on pressure over the right upper abdomen and the epigastrium.

INVESTIGATIONS

Erythrocyte sedimentation rate was increased; as were the transaminases and cholestasis parameters. Ultrasonography and computed tomography of the abdomen revealed an echo-poor mass with cystic areas in the region of the head of the pancreas, as well as extra- and intrahepatic dilatation of the biliary tract. Endoscopic retrograde cholangiopancreatography failed to demonstrate a ductal pancreatic carcinoma. Biopsies of a macroscopically peculiar-looking duodenal ulcer demonstrated a noncaseous epithelioid granuloma. A fine-needle biopsy was performed for further diagnosis.

DIAGNOSIS, TREATMENT AND COURSE

Histological examination of the needle biopsy revealed a caseous granuloma and acid-fast bacteria. The tuberculin test (GTI) was strongly positive (14-15 mm), indicating tuberculosis of the pancreas and duodenum. Multiple tuberculostatics rapidly improved the patient's symptoms, and the further course was without complications.

CONCLUSION

Tuberculosis should be included in the differential diagnosis of consumptive disease with an atypical presentation, especially because treatment could well be curative.

CD4+ and CD8+ clonal T cell expansions indicate a role of antigens in ankylosing spondylitis; a study in HLA-B27+ monozygotic twins

Ankylosing spondylitis (AS) is a complex genetic disease in which both MHC and non-MHC genes determine disease susceptibility. To determine whether the T cell repertoires of individuals with AS show signs of increased stimulation by exogenous antigens, CD4+ and CD8+ T cell subsets of five monozygotic HLA-B27+ twins (two concordant and three discordant for AS) and CD8+ T cell repertoires of three healthy HLA-B27+ individuals were characterized by TCR beta-chain (TCRB) CDR3 size spectratyping. Selected TCRB-CDR3 spectra were further analysed by BJ-segment analysis and TCRB-CDR3 from expanded T cell clones were sequenced. In an analysis of all data (519/598 possible TCRB-CDR3 spectra), AS was associated with increased T cell oligoclonality in both CD8+ (P = 0.0001) and CD4+ (P = 0.033) T cell subsets. This was also evident when data were compared between individual twins. Nucleotide sequence analysis of expanded CD8+ or CD4+ T cell clones did not show selection for particular TCRB-CDR3 amino acid sequence motifs but displayed sequence homologies with published sequences from intra-epithelial lymphocytes or synovial T cells from rheumatoid arthritis patients. Together, these results provide support for the hypothesis that responses to T cell-stimulating exogenous or endogenous antigens are involved in the induction and/or maintenance of AS.

Identical T-cell expansions in the colon mucosa and the synovium of a patient with enterogenic spondyloarthropathy

Intestinal T lymphocytes activated by antigen are suspected to play a key role in enterogenic spondyloarthropathies (SpA). Therefore, we aimed to identify and functionally characterize T-cell clones that are coexpanded in the intestinal mucosa and the synovium. Colon, peripheral blood, and synovium of a patient with enterogenic SpA were screened for clonal T-cell expansions by TCRB-CDR3 length analysis and sequencing. T-cell clones expanded in vivo were isolated from archived synovial cells by targeted T-cell cloning and characterized for phenotype, cytokine production, and antigen specificity. The synovial TCRBV18(+) T-cell repertoire of the patient was dominated by 2 CD8(+) T-cell clones using related CDR3. Both clones were expanded throughout the colon and were present in the peripheral blood. Upon in vitro stimulation with PDB/ionomycin, they showed predominantly interferon gamma and interleukin (IL)-4 but also tumor necrosis factor alpha and IL-10 production and did not specifically lyse autologous T-cell blasts, B-cell lines, or other autologous or allogeneic target or CD1d-transfected cells. These findings strongly suggest that T lymphocytes activated by antigen in the intestinal mucosa contribute to joint inflammation in enterogenic SpA by recognition of antigens specific for the inflamed synovium.

[Crohn disease, ulcerative colitis. When bacteria attack the intestinal wall....]

Crohn's disease (CD) and ulcerative colitis (UC) are clinical entities characterized by spontaneous relapses and are thought to be caused in large part by a dysregulated immune response to inflammatory stimuli. Specific infectious agents or antigens inducing or perpetuating inflammation, however, are not known. Recent results in contrast support the hypothesis, that the normal intestinal flora plays a central role in the pathogenesis of both diseases. Studies performed with E. coli Nissle 1917 demonstrated that this bacterium can positively affect the course of disease in UC and CD patients. The clinical efficacy of probiotics can yield valuable information about disease pathogenesis and, as a modification of current standard therapy, opens new and interesting therapeutic alternatives.

Induction of cytokine production in naive CD4(+) T cells by antigen-presenting murine liver sinusoidal endothelial cells but failure to induce differentiation toward Th1 cells

BACKGROUND & AIMS

Murine liver sinusoidal endothelial cells (LSECs) constitutively express accessory molecules and can present antigen to memory Th1 CD4(+) T cells. Using a T-cell receptor transgenic mouse line, we addressed the question whether LSECs can prime naive CD4(+) T cells.

METHODS

Purified LSECs were investigated for their ability to induce activation and differentiation of naive CD4(+) T cells in comparison with bone marrow-derived antigen-presenting cells and macrovascular endothelial cells. Activation of T cells was determined by cytokine production. LSECs were further studied for expression of interleukin (IL)-12 by reverse-transcription polymerase chain reaction, and the unique phenotype of LSECs was determined by flow cytometry.

RESULTS

We provide evidence that antigen-presenting LSECs can activate naive CD62Lhigh CD4(+) T cells. Activation of naive CD4(+) T cells by LSECs occurred in the absence of IL-12. In contrast, macrovascular endothelial cells from aorta could not activate naive CD4(+) T cells. The unique functional characteristics of microvascular LSECs together with a unique phenotype (CD4(+), CD11b+, CD11c+, CD80(+), CD86(+)) make these cells different from macrovascular endothelial cells. Furthermore, LSECs did not require in vitro maturation to activate naive CD4(+) T cells. Most importantly, LSECs failed to induce differentiation toward Th1 cells, whereas conventional antigen-presenting cell populations induced a Th1 phenotype in activated CD4(+) T cells. Upon restimulation, CD4(+) T cells, which were primed by antigen-presenting LSECs, expressed interferon gamma, IL-4, and IL-10, which is consistent with a Th0 phenotype. Exogenous cytokines (IL-1beta, IL-12, or IL-18) present during T-cell priming by antigen-presenting LSECs could not induce a Th1 phenotype, but neutralization of endogenously produced IL-4 during T-cell priming led to a reduced expression of IL-4 and IL-10 by CD4(+) T cells upon restimulation. The addition of spleen cells to cocultures of LSECs and naive CD4(+) T cells during T-cell priming led to differentiation of T cells toward a Th1 phenotype.

CONCLUSIONS

The ability of antigen-presenting LSECs to induce cytokine expression in naive CD4(+) T cells and their failure to induce differentiation toward a Th1 phenotype may contribute to the unique hepatic microenvironment that is known to promote tolerance.

T cell specificity and cross reactivity towards enterobacteria, bacteroides, bifidobacterium, and antigens from resident intestinal flora in humans

BACKGROUND

T cell responses to normal intestinal bacteria or their products may be important in the immunopathogenesis of chronic enterocolitis.

AIMS

To investigate the T cell specificity and cross reactivity towards intestinal bacteria.

PATIENTS/METHODS

T cell clones were isolated with phytohaemagglutinin from peripheral blood and biopsy specimens of inflamed and non-inflamed colon from five patients with inflammatory bowel disease (IBD) and two controls. T cell clones were restimulated with anaerobic Bacteroides and Bifidobacteria species, enterobacteria, and direct isolates of aerobic intestinal flora. T cell phenotype was analysed by single-cell immunocyte assay.

RESULTS

Analysis of 96 T cell clones isolated from peripheral blood and biopsy specimens from two patients with IBD showed that both Bifidobacterium and Bacteroides species specifically stimulate proliferation of CD4+TCRalphabeta+ T cell clones from both sites and that cross reactivity exists between these anaerobic bacteria and different enterobacteria. Analysis of 210 T cell clones isolated from three patients with IBD and two controls showed that indigenous aerobic flora specifically stimulate T cell clones from peripheral blood and biopsy specimens from a foreign subject. Some of these flora specific T cell clones were cross reactive with defined enterobacteria. In addition, T cell clones stimulated by their own indigenous aerobic flora were identified in patients with IBD.

CONCLUSION

Immune responses to antigens from the intestinal microflora involve a complex network of T cell specificities.

Anti-TNF antibody in Crohn's disease--status of information, comments and recommendations of an international working group

The chimeric anti-TNF antibody Remicade (Infliximab) has recently been approved for human use by the FDA and is now available on the market. Since there is considerable interest in this kind of treatment among patients with Crohn's disease, an international working group has summarized the presently available information about efficacy, side effects and possible problems of this treatment. Studies show that Remicade is effective in the treatment of active Crohn's disease, maintaining remission and fistulae. The working group does not see Infliximab as a first-line treatment for Crohn's disease. It may be used in active phase recurrent disease, chronic active disease and fistulae if standard treatment was not successful. For the surveillance special attention has to be given to the unknown malignancy rate of Infliximab. Infusion should be performed in an institution, routinely performing intravenous infusions and a two-hour surveillance of the patients should be guaranteed to recognize anaphylactic reactions or acute side effects. There is presently no information indication that the combination with immunosuppressants might increase risks or side effects of this treatment. Due to the limited information available the working group would prefer to use Remicade in studies only and recommends central collection and documentation of all data on efficacy and side effects for the next year.

IgG, albumin, and sCD44 in whole-gut lavage fluid are useful clinical markers for assessing the presence and activity of pouchitis

Pouchitis is the most significant long-term complication in patients with ileoanal pouch anastomosis (IAP) and is especially frequent in patients with ulcerative colitis. There is an urgent need for simple and objective parameters to assess the presence and activity of pouchitis. Whole-gut lavage fluid (WGLF) was collected from 34 patients [8 with pouchitis (PDAI > or = 7 points) and 26 without pouchitis (Pouchitis Disease Activity Index, PDAI, < 7)]. Patients with active ulcerative colitis (n = 8) served as controls. Concentrations of IgG and sCD44 in WGLF were measured by enzyme-linked immunosorbent assays and those of albumin by immunoturbidimetry. Similar to the case in active ulcerative colitis, concentrations of IgG, albumin, and sCD44 in WGLF were significantly increased in acute pouchitis and reached high specificity (IgG 96%, albumin 96%, sCD44 100%) and acceptable sensitivity (75%) for the diagnosis of acute pouchitis. These parameters were also closely correlated with disease activity as determined by PDAI and endoscopic scoring indices. Assay of protein concentrations in WGLF is thus a simple and objective means for grading inflammation of the pouch and may be useful as a quantitative index of disease activity in clinical studies.

Cellular and humoral immunity to the 60-kD heat shock protein in inflammatory bowel disease

BACKGROUND

Mycobacteria have been considered a possible etiological agent in Crohn's disease. Since cross-reactivity between epitopes of mycobacterial and self-heat shock protein might represent a potential disease mechanism, we determined the cellular and humoral immune responses to the mycobacterial and the human 60-kD heat shock protein, as well as various control antigens.

METHODS

We studied samples from 19 patients with Crohn's disease, 12 patients with ulcerative colitis, and from 19 healthy individuals. T cell responses were studied using a standard proliferation assays to purified recombinant mycobacterial and human 60-kD heat shock protein. Antibody levels were measured by establishing an enzyme-linked immunosorbent assays to recombinant purified 60-kD heat shock protein.

RESULTS

The proliferative responses to the mycobacterial and the human 60-kD heat shock protein were closely correlated, but the cellular immune response to both antigens was not significantly different between the two patient groups and healthy controls. In addition, antibody levels to heat shock protein were also not significantly different between the three groups.

CONCLUSIONS

These results argue strongly against a role for mycobacterial heat shock protein in the pathogenesis of Crohn's disease. However, in view of previous data demonstrating overexpression of 60-kD heat shock protein in inflammatory Crohn's disease tissue, this considerable cellular and humoral autoreactivity suggests an important immunoregulatory role for the 60-kD heat shock protein.

Interleukin-10 expression is autoregulated at the transcriptional level in human and murine Kupffer cells

Interleukin 10 (IL-10) is known to downregulate immune responses. The regulation of IL-10 gene expression therefore determines the outcome of local immune reactions. We investigated time course and downregulation of IL-10 production in primary Kupffer's cells (KC), which are known to secrete IL-10 in response to endotoxin challenge. Human and murine KC were isolated by centrifugal elutriation and investigated for IL-10 gene expression by a two-step amplification procedure (reverse transcriptase-polymerase chain reaction [PCR] followed by T7-polymerase chain reaction). We show that IL-10 messenger ribonucleic acid (mRNA) showed a >450 fold increase in KC 2 hours after endotoxin challenge. IL-10 protein release from KC strictly depended on de novo protein synthesis. Endotoxin mediated increase in IL-10 gene expression was downregulated by exogenous (>350-fold reduction of IL-10 mRNA level), as well as endogenous IL-10 protein, showing a negative autoregulatory feedback loop. IL-10 receptor expression was found to be constitutive and functional in KC. Early expression of IL-10 in KC may be of functional relevance to the outcome of immune and inflammatory reactions in the liver sinusoid. The negative autoregulation of IL-10 expression may represent a mechanism to regain a state of functional responsiveness in the microenvironment towards new proinflammatory stimuli. In conclusion, autoregulatory downregulation of IL-10 expression in KC may account for important regulatory steps of local immune response in the liver sinusoid.

Normal interleukin-12 production in individuals with antibodies to Helicobacter pylori

It is increasingly recognized that the inability of the immune system to clear H. pylori infection is caused by an inadequate immune response and is associated with chronic gastric inflammation. To further investigate the cellular immune response to H. pylori, we studied PBMC from 31 H. pylori antibody-negative and 16 H. pylori antibody-positive individuals for H. pylori-induced DNA synthesis, secretion of the Th1-type cytokine IFN-gamma and secretion of IL-12, a cytokine produced by bacteria-stimulated monocyte/macrophages and a potent inducer of antibacterial immune responses and Th1-type T cells. All experiments were performed using Y. enterocolitica 03 as control. Our results demonstrate that DNA synthesis, IFN-gamma production and IL-12 production induced by H. pylori or Y. enterocolitica 03 did not differ significantly between H. pylori antibody-positive and H. pylori antibody-negative individuals. However, in the H. pylori-positive group there was a tendency, although not statistically significant, to produce less IFN-gamma in response to H. pylori but not Y. enterocolitica. These results demonstrate that monocyte/macrophages from H. pylori-positive individuals secrete normal amounts of IL-12 upon bacterial challenge and suggest that the decreased production of IFN-gamma in H. pylori-positive individuals observed in previous studies is selective for H. pylori and not caused by decreased IL-12 secretion.

Dominant TCRB-V-J chain usage and clonal expansion of sarcoma-reactive CD4+ HLA-DR-restricted T cells suggest a limited set of immunodominant sarcoma antigens

Tumor-reactive CD4+ T cells have been isolated from tumor patients, and their specifity but not T-cell receptor (TCR) repertoire has been analyzed. Since we have described CD4+ sarcoma-reactive T-cell clones, we now sought to determine whether the TCR repertoire of these clones provides information on the spectrum of recognized sarcoma antigens. We analyzed the TCR beta (TCRB) chain repertoire of 19 CD4+ HLA-DR-restricted T-cell clones reactive with the autologous sarcoma cell line MZ-MES-1, with HLA-DR-matched tumor cell lines of different tissue origins and B-cell blasts. We identified 7 different clonotypes, which used a limited set of TCRBV and TCRBJ segments. Although the CDR3 of the different clonotypes was diverse, repeated restimulation with sarcoma cells led to a monoclonal expansion of T cells with particular TCR clonotypes in 5/6 mixed lymphocyte tumor cell cultures (MLTC). One clonotype was found in 2 independent MLTC experiments. Sarcoma-reactive T cells were demonstrated in patient tumor-infiltrating lymphocytes (TIL) and peripheral blood mononuclear cells (PBMC) by clonotypic PCR. Our results indicate a limited number of immunodominant antigens expressed by the sarcoma cells. The junctional diversity of the TCR clonotypes shows that these antigens did not lead to extensive negative thymic selection as classical autoantigens would have. Therefore, the recognized antigens might represent cryptic autoantigens related to cellular transformation or proliferation.

[Follow-up of Crohn's disease: can hydro-MRI replace fractionated gastrointestinal passage examination?]

PURPOSE

To compare the value of hydro-MRI with follow-through examinations in the follow-up of Crohn's disease.

METHOD

22 patients known to be suffering from Crohn's disease were examined via 1.5 T-MR system; an oral contrast examination using 1000 ml of a 2.5% mannitol solution was performed in all patients. T2-weighted TSE sequences and T1-weighted SE sequences were performed before and after the intravenous injection of Gd-DTPA. To reduce movement artifacts caused by peristalsis of the gut, intravenous injection of 40 mg Buscopan was given. The findings of hydro-MRI were compared with the follow-through examinations.

RESULTS

In the upper gastrointestinal tract, the follow-through examination showed clear advantages compared with hydro-MRI for the demonstration of inflammatory changes in the gut; Hydro-MRI was, however, somewhat more reliable in the ileum and colon. It was also more sensitive than the follow-through for the demonstration of enteric fistulae (four as compared with two cases), and in demonstration extraluminal changes (free fluid in six against zero, and inflammatory adherent loops (four against zero)). Amongst the 22 patients, hydro-MRI was equal (in 10) or better (in 8) than the follow-through examination for demonstrating the intestinal manifestations of Crohn's disease, and follow-through was better in only four.

CONCLUSION

For follow-up of Crohn's disease, hydro-MRI is at least as good as follow-through examination, and is even preferable, because of the absence of radiation exposure of the usually young patients.

Immune responses towards intestinal bacteria--current concepts and future perspectives

The intestinal mucosa constitutes an important barrier as it separates each individual from a large array of antigens within the bowel lumen. These luminal antigens may either be derived from pathogens or may be derived from harmless constituents such as ingested food or the normal intestinal flora. The dichotomy of potentially harmful and potentially harmless antigens encountered by the mucosal immune system poses the important task that, with regard to bacteria-derived antigens, the gut associated immune system is required to mount an efficient host defense against pathogenic bacteria but to maintain at the same time the regulatory control mechanisms which protect the human organism from hyperresponsiveness, and thus chronic inflammation, towards antigens from the normal intestinal flora. In the present review, we discuss variable host and bacterial factors which are likely to determine whether the immune response to pathogenic or normal intestinal bacteria will have beneficial or detrimental consequences for the human organism. Using infections with the prototype enteropathogens V. cholerae and enteropathogenic E. coli (ETEC), Y. enterocolitica induced reactive arthritis (ReA) and in more detail, inflammatory bowel diseases (IBD) as exemplary clinical situations, we review current hypotheses of how bacteria or their products are encountered by cellular components of the specific immune system and how this may relate to disease pathogenesis and the development of new treatment strategies.

Regulation of endotoxin-induced IL-6 production in liver sinusoidal endothelial cells and Kupffer cells by IL-10

Sinusoidal endothelial cells and Kupffer cells are the first cell populations in the liver that come into contact with gut-derived endotoxin in portal blood. Although endotoxin concentrations as high as 1 ng/ml are physiologically present in portal blood, no local inflammation is seen. We show that the proinflammatory cytokine IL-6, which is central to the development of inflammatory reactions in the liver, is produced by sinusoidal endothelial cells and Kupffer cells in response to low concentrations of endotoxin (100 pg/ml to 1 ng/ml). The anti-inflammatory cytokine IL-10 down-regulated endotoxin-induced IL-6 release in endothelial and Kupffer cells. Importantly, Kupffer cells secreted IL-10 after endotoxin stimulation and may therefore participate in the local regulation of inflammation. We have found that IL-6 secretion in Kupffer cells is tightly regulated by endogenous IL-10, because increased IL-6 secretion resulted when neutralizing antibodies to IL- 10 were added to resting and endotoxin-challenged Kupffer cells. Furthermore, repeated exposure of endothelial cells to endotoxin induced a state of tolerance which resulted in decreased release of IL-6 in response to a second endotoxin challenge. Our results support the notion that inflammatory reactions in the liver in response to endotoxin are down-regulated by local release of the anti-inflammatory cytokine IL-10 that is produced by Kupffer cells.

TCRB junctional regions from HLA-B27-restricted T cells and HLA-B27 binding peptides display conserved hydropathy profiles in the absence of primary sequence homology

Analysis of formal amino acid sequence identity between different TCRB chain (TCRB) hypervariable regions (CDR3) is commonly used to localize relevant sites of TCR antigen interaction or to yield indirect information on unknown corresponding antigens. However, this analysis sometimes fails to demonstrate expected concordances, e.g. between CDR3 from T cell clones of identical reactivity. Since this may be due to ignorance of physico-chemical parameters, we have now use hydropathy profile analysis as an additional method to examine TCRB-CDR3 and putative peptide antigens. Superimposed hydropathy plots (SHOP) of 20 TCRB-CDR3 from HLA-B27-restricted autoreactive and Yersinia enterocolitica-specific synovial cytotoxic T lymphocytes (CTL) isolated from patients with reactive arthritis (ReA) revealed restricted distribution of polar amino acids resulting in characteristically different SHOP profiles between the two CTL groups. Similarly, Yersinia-derived and self nonapeptides known to bind HLA-B27 differed in SHOP profiles. To validate the method we have extended SHOP analysis to published TCRB sequence data from additional TCRB-CDR3 from peptide-specific CTL but not in TCRB from HLA-B27-alloreactive CTL or non-HLA-B27-restricted control CTL. We here demonstrate that SHOP may improve TCR-CDR3 sequence analysis by detection of structural constraints which remain cryptic by conventional sequence analysis. Our data suggest that electrostatic properties rather than rigid sequence motifs determine T cell specificities.

Reciprocal regulation of mucosal surface IgA+ B cells by Ig receptor cross-linking and CD40 ligand

In the present study, we analyze the role of Ig receptor cross-linking in T cell-dependent stimulation of both preswitch (surface IgM+ (sIgM+/sIgD+) B cells and postswitch (sIgA+) B cells. We demonstrate that purified sIgA+ B cells pretreated with anti-IgA-dextran at low concentrations (10 and 100 ng/ml) exhibited an increased response to activated T cells, whereas pretreatment with higher doses (1 and 10 micrograms/ml) led to a profound suppression of IgA secretion (> or = 90%). The suppressive effect of anti-IgA-dextran was accentuated in the presence of IL-2 and attenuated in the presence of IL-4. Anti-IgA-dextran pretreatment had no effect on sIgA+ B cell survival. sIgM+/sIgD+ B cells pretreated with anti-IgD-dextran or anti-IgM-dextran did not show significant inhibition. The increased susceptibility of sIgA+ B cells, but not of sIgM+/sIgD+ B cells, to Ig cross-linking-mediated suppression was confirmed in cross-linking studies with the same Ab (anti-kappa-dextran). Importantly, anti-IgA-dextran-mediated suppression could be reversed by stimulation of sIgA+ B cells with fibroblasts expressing CD40L; such a reversal required persistent exposure to cells expressing high levels of CD40L. These studies imply that Ig receptor cross-linking renders postswitch sIgA+ B cells unresponsive to subsequent stimulation via activated T cells, but this unresponsiveness is overcome by a persistent high level CD40L signal.

Reciprocal regulation of mucosal surface IgA+ B cells by Ig receptor cross-linking and CD40 ligand

In the present study, we analyze the role of Ig receptor cross-linking in T cell-dependent stimulation of both preswitch (surface IgM+ (sIgM+/sIgD+) B cells and postswitch (sIgA+) B cells. We demonstrate that purified sIgA+ B cells pretreated with anti-IgA-dextran at low concentrations (10 and 100 ng/ml) exhibited an increased response to activated T cells, whereas pretreatment with higher doses (1 and 10 micrograms/ml) led to a profound suppression of IgA secretion (&gt; or = 90%). The suppressive effect of anti-IgA-dextran was accentuated in the presence of IL-2 and attenuated in the presence of IL-4. Anti-IgA-dextran pretreatment had no effect on sIgA+ B cell survival. sIgM+/sIgD+ B cells pretreated with anti-IgD-dextran or anti-IgM-dextran did not show significant inhibition. The increased susceptibility of sIgA+ B cells, but not of sIgM+/sIgD+ B cells, to Ig cross-linking-mediated suppression was confirmed in cross-linking studies with the same Ab (anti-kappa-dextran). Importantly, anti-IgA-dextran-mediated suppression could be reversed by stimulation of sIgA+ B cells with fibroblasts expressing CD40L; such a reversal required persistent exposure to cells expressing high levels of CD40L. These studies imply that Ig receptor cross-linking renders postswitch sIgA+ B cells unresponsive to subsequent stimulation via activated T cells, but this unresponsiveness is overcome by a persistent high level CD40L signal.

Bacteria-specific T-cell clones are selective in their reactivity towards different enterobacteria or H. pylori and increased in inflammatory bowel disease

In the present study the authors investigated the T-cell response to different enterobacteria or Helicobacter pylori and tested the hypothesis that the frequency of bacteria-specific T cells is increased in the intestine of patients with active inflammatory bowel disease (IBD), i.e. Crohn's disease (CD) and ulcerative colitis (UC). The analysis of a large panel of T-cell clones (Tc) (n = 888) from peripheral blood, non-inflamed and inflamed intestine from IBD patients and control individuals shows that both peripheral blood and intestinal T-cell clones were selectively stimulated by either Salmonella typhimurium, Yersinia enterocolitica 03, Escherichia coli or Helicobacter pylori sonicates, that only < 3% of all bacteria-reactive Tc were crossreactive and that proliferation to bacterial sonicates was inhibited by anti-MHC class II antibody. In addition, bacteria-specific Tc from IBD patients were more frequently isolated from inflamed intestine than from peripheral blood (P = 0.0039) or non-inflamed intestine. These data, from a large number of T-cell clones, are the first systematic analysis describing the response of individual T cells towards different bacterial species (ssp.). They show that T cells with specificity for distinct antigens or superantigens that are characteristic for a defined bacteria ssp. are present in normal, and increased in inflamed, IBD-intestine. These bacteria-specific Tc may play a role in IBD pathogenesis.

[Enteropathic spondylarthritis in chronic inflammatory bowel diseases: prevalence, manifestation pattern and HLA association]

BACKGROUND

Enteropathic spondylarthropathies (SpA) are the most frequent extraintestinal manifestation of the chronic inflammatory bowel disease (IBD), Crohn's disease (CD) and Ulcerative Colitis (UC). It was the aim of the present study, to analyze a large number of IBD patients for the prevalence and pattern of joint manifestation and the association of SpA with the extend of bowel involvement and HLA-haplotype.

PATIENTS AND METHODS

521 patients (409 CD and 112 UC) were prospectively analyzed over a period of one year. SpA was diagnosed on the basis of an appropriate patient history as well as clinical, radiological and immunoserological parameters.

RESULTS

SpA was diagnosed in 10.7% of all CD and 14.4% of all UC patients. In 26.8% of all patients symptoms of SpA occurred prior to and in 14.4% simultaneously with IBD. 28.1% of all patients presented with isolated peripheral arthritis, 26.8% of all patients showed an isolated involvement of the spine or sacroiliic joints and 45.1% of all patients presented with combined involvement. 2/12 UC patients with SpA suffered from rectosigmoiditis, 5/12 from partial colitis and 5/12 had pancolitis. In CD patients with SpA, 8/59 had isolated colitis, 8/59 ileocolitis and 31/59 isolated small bowel involvement. There was a positive correlation between SpA and HLA-B27 (p < 0.01).

CONCLUSION

Enteropathic spondylarthropathies are an important extraintestinal manifestation of IBD. Spondylarthropathies occur irrespective of the extend of IBD and frequently become symptomatic prior to IBD. These and recent data describing inflammatory bowel disease in patients with SpA of unknown etiology suggest that both diseases have a common pathogenetic background.

Rare pre-core stop-codon mutant nt. 1897 predominates over wide-spread mutant nt. 1896 in an unusual course of chronic hepatitis B

We present a patient with an unusual course of hepatitis B e antigen (HBeAg)-negative chronic hepatitis B who had repeated reactivations of his disease progressing to cirrhosis with terminal liver failure. Each flare up presented like an acute hepatitis with very high titres of hepatitis B virus (HBV) and high inflammatory activity followed by rapid clearance of viraemia. The pre-core genome of HBV isolated from sera during 5 years of follow up was analysed. Direct sequencing of polymerase chain reaction (PCR) products derived from consecutive sera showed a rare pre-core stop-codon mutation at nucleotide (nt.) 1897 G --> A with an accompanying mutation nt. 1857 C --> T as well as a stop-codon mutation nt. 1896 G --> A. By cloning and sequencing of PCR products the mutant strain with mutation nt. 1897 was shown to predominate over viral strains with a mutation nt. 1896 during the course of disease, although the stop-codon mutation nt. 1896 in general is observed more frequently. Both mutations allow viral replication by stabilizing the encapsidation signal 'epsilon'. This allowed HBV replication at a very high level as observed during flare ups. The absence of HBeAg may be responsible for the massive cytotoxic T-cell response towards hepatocytes which might explain the rapid progression to liver cirrhosis although no, or very little, HBV replication was observed for long periods. However, there is no clear explanation as to why the nt. 1897 mutant strain overwhelmed the other virus strains.

Tolerance towards resident intestinal flora in mice is abrogated in experimental colitis and restored by treatment with interleukin-10 or antibodies to interleukin-12

There is now increasing evidence that hyperresponsiveness towards intestinal flora is a crucial event in the pathogenesis of inflammatory bowel disease (IBD). In support of this hypothesis, we recently described in humans that tolerance exists towards indigenous intestinal flora but is broken in active IBD lesions. In the present study, we have attempted to transfer this model into mice from different genetic backgrounds (BALB/c, SJL/J, C3H/HeJ). We found that mononuclear cells from spleen, small bowel and large bowel of mice do not proliferate, i.e. are tolerant when exposed to bacterial sonicates derived from autologous intestine (BsA) but do proliferate, i.e. are immune when exposed to bacterial sonicates derived from the heterologous intestine of syngenic littermates (BsH). Furthermore, we demonstrate that both local and systemic tolerance to BsA is broken in a murine model of chronic intestinal inflammation induced by the hapten reagent 2, 4, 6-trinitrobenzene sulfonic acid (TNBS), which mimics several important characteristics of Crohn's disease. Tolerance to BsA was restored and TNBS-induced colitis was abrogated in mice systemically treated with interleukin (IL)-10 or antibodies to IL-12. Treatment specifically restored tolerance to BsA, but did not suppress proliferation to BsH. In summary, we here report a new model for the study of immunity and tolerance towards bacterial products. Our data suggest that tolerance to BsA is an important protective mechanism and that restoration of tolerance intestinal flora by IL-10 and antibodies to IL-12 may be of potential therapeutic utility in patients with inflammatory bowel disease.

Antibodies to proteinase 3 mediate expression of vascular cell adhesion molecule-1 (VCAM-1)

VCAM-1 was first identified as an adhesion molecule induced on human endothelial cells (HEC) by inflammatory cytokines such as IL-1, tumour necrosis factor (TNF), and lipopolysaccharide (LPS). The molecule binds to a variety of leucocytes, including B cells, T cells, basophils, eosinophils and monocytes. Vascular expression of VCAM-1 has been associated with a number of disease states, including rheumatoid arthritis and vasculitis. The detection of anti-neutrophil cytoplasmic antibodies (ANCA), especially to proteinase 3 (PR3), has become important in the diagnosis of Wegener's granulomatosis (WG) and related vasculitides. Recently we were able to demonstrate a direct effect of anti-PR3 antibodies on neutrophil-endothelial interactions (Blood 1993; 82:1221). Binding of anti-PR3 antibodies to their antigen translocated into the membrane of HEC leads to an enhanced adhesion of neutrophils via induction of E-selectin (Clin Exp Immunol 1993; 94:440). The aim of this study was to investigate the effect of anti-PR3 antibodies on the expression of VCAM-1. HEC were isolated from umbilical vein and cultured on microtitre plates. After preincubation with purified anti-PR3 antibody, purified control antibodies (SS-A, SS-B, RNP) (IgG and F(ab')2 fragments) or different cytokines (controls), VCAM-1 was detected on the surface of unfixed HEC by cyto-ELISA and polymerase chain reaction analysis. Incubation of HEC with anti-PR3 antibodies led to a marked increase of endothelial VCAM-1 expression with a peak after 8 h. Incubation with TNF-alpha also led to maximal VCAM-1 expression after 4-6 h (control). Increased adhesion of T lymphocytes to HEC after binding of anti-PR3 antibodies to their antigen could be confirmed by performing adherence assays. This effect could be inhibited by antibodies to VLA-4. In conclusion, we have been able to show that cytokine-like effects of anti-PR3 antibodies on HEC are not limited to induction of neutrophil adhesion. Anti-PR3 antibodies may thus contribute to the regulation of T lymphocyte migration from the blood by HEC in ANCA-related vasculitides.

HLA-B27-restricted cytotoxic T lymphocyte responses to arthritogenic enterobacteria or self-antigens are dominated by closely related TCRBV gene segments. A study in patients with reactive arthritis

Identification of the T-cell receptors (TCR) used by synovial cytotoxic T lymphocytes (CTL) of patients with reactive arthritis (ReA) may be crucial to better understanding the pathogenetic mechanism underlying the HLA-B27 association of spondylarthropathies. The authors, therefore, sequenced 25 TCRB chains from HLA-B27-restricted CD8+ CTL clones and two clonal lines specific for self- or Yersinia enterocolitica antigen isolated from synovial fluids of 3 HLA-B27+ patients with ReA and PBL of one healthy HLA-B27+ individual. Fourteen non-HLA-B27-restricted CTL served as controls. Both autoreactive and Y. enterocolitica specific HLA-B27-restricted CTL used a highly limited set of VB genes with preferential rearrangement of three closely related VB families (VB 13, 14, 17), suggesting that these families contain a preferred site for contact with the HLA-B27 molecule. In addition, the presence of limited TCRBJ usage, limited heterogeneity in CDR3 sequences and dominant clones from individual donors among these CTL indicate that TCRB chain usage is further restricted by a limited set of peptides bound to the HLA-B27 molecule. Limited TCR usage by SF CTL of ReA patients may lay a basis for therapeutical manipulation of the T-cell response in the spondylarthropathies.

The T cell receptor (TCR) in HLA-B27-restricted T cell responses--an introduction

Recent data indicate that cytotoxic T lymphocytes (CTL) are involved in the pathogenesis of HLA-B27-associated spondylarthropathies. In the absence of clearly defined "arthritogenic" bacterial or self peptides that are presented by HLA-B27 and recognized by such CD8+CTL, one approach has been to investigate the T cell repertoire of lesional cellular infiltrates by determining T cell receptor (TCR) variable (V) gene segment frequencies. Furthermore, the TCR V alpha and V beta chains of HLA-B27-restricted CTL clones, notably the putative peptide-contacting CDR3-regions of these TCRs, have been sequenced. This article will give a short review of the current literature on the topology of the TCR and its hypervariable CDR3 region, TCR repertoire diversity in rheumatic diseases and will concentrate on TCR V alpha and V beta gene usage in HLA-B27-restricted T cell responses.

Differential usage of T-cell receptor V beta gene families by CD4+ and CD8+ T cells in patients with CD8hi common variable immunodeficiency: evidence of a post-thymic effect

In this study, we report that differences between T-cell receptor (TCR) V beta gene family usage in CD4+ and CD8+ T cells are significantly greater in a subgroup of patients with common variable immunodeficiency (CVI) and high levels of activated CD8+ T cells (CD8hi CVI) than in controls (P < 0.001). In CD8hi CVI patients, such differences were also significantly greater for V beta 12 than for other V beta families. As the causes of the differential usage of V beta gene families by CD4+ and CD8+ T cells are under investigation, it was interesting that the combined differences between V beta gene family usage in the CD4+ and CD8+ T-cell subpopulations as a whole were significantly lower than the combined differences between individual V beta gene family usage in either CD4+ or CD8+ T-cell subpopulations (P < 0.001 in both control and CD8hi CVI patients). Further, the pattern of V beta gene family usage in CD4+ T cells was remarkably similar to that in CD8+ T cells in both groups. These data strongly suggest that differences in V beta gene family usage arising from coselection by major histocompatibility complex (MHC) class I versus MHC class II restriction elements do not fundamentally distort 'basic' V beta gene family usage patterns. They also support the concept that differences in CD4+ and CD8+ T-cell V beta gene family usage, which were increased in CD8hi CVI, can arise from high-affinity interactions between disease-associated antigens or superantigens and T cells in the post-thymic T-cell compartment.

Tolerance exists towards resident intestinal flora but is broken in active inflammatory bowel disease (IBD)

Hyporesponsiveness to a universe of bacterial and dietary antigens from the gut lumen is a hallmark of the intestinal immune system. Since hyperresponsiveness against these antigens might be associated with inflammation, we studied the immune response to the indigenous intestinal microflora in peripheral blood, inflamed and non-inflamed human intestine. Lamina propria monocuclear cells (LPMC) isolated from inflamed intestine but not peripheral blood mononuclear cells (PBMC) of IBD patients with active inflammatory disease strongly proliferated after co-culture with sonicates of bacteria from autologous intestine (BsA). Proliferation was inhibitable by anti-MHC class II MoAb, suggesting that it was driven by antigen. LPMC from adjacent non-inflamed intestinal areas of the same IBD patients and PBMC or LPMC isolated from non-inflamed intestine of controls and patients with IBD in remission, in contrast, did not proliferate. PBMC or LPMC which had been tolerant to bacteria from autologous intestine, however, strongly proliferated after co-culture with bacterial sonicates from heterologous intestine (BsH). This proliferation was associated with an expansion of CD8+ T cells, increased expression of activation markers on both CD4+ and CD8+ lymphocyte subsets, and production of IL-12, interferon-gamma (IFN-gamma), and IL-10 protein. These results show that tolerance selectively exists to intestinal flora from autologous but not heterologous intestine, and that tolerance is broken in intestinal inflammation. This may be an important mechanism for the perpetuation of chronic IBD.

Synovial fluid MHC-unrestricted gamma delta-T lymphocytes contribute to antibacterial and anti-self cytotoxicity in the spondylarthropathies

OBJECTIVE

In reactive arthritis (ReA), synovial fluid-derived bacteria-specific CD4+ and CD8+ T cells have been studied intensively in recent years. We have addressed the question whether gamma delta-TCR+ lymphocytes could contribute to antibacterial or anti-self cytotoxicity in the affected joints of patients, with spondylarthropathies.

METHODS

T cell clones were derived by random cloning from the synovial fluids of one patient with Yersinia-induced ReA, one patient with a Yersinia-induced flare up of pre-existing ankylosing spondylitis, and one patient with ankylosing spondylitis. Eight clones with a CD3+, alpha beta-TCR-, CD4-, CD8- and gamma delta-TCR+ phenotype (all expressing V gamma 9) were tested in a standard 52Cr-release assay using autologous or allogeneic B cell lines, CIR-B27, Daudi cells, and RJ.225 cells.

RESULTS

Four gamma delta-TCR+ clones killed both autologous and allogeneic target cells when infected with live Yersinia or Salmonella and also uninfected Daudi cells expressing GroEL heatshock protein. One clone was specific for Yersinia-infected targets. Three gamma delta-TCR+ clones were cytotoxic when uninfected autologous or allogeneic targets were employed. Polymorphic "classical" MHC class I or class II molecules were not used as restriction elements.

CONCLUSION

We conclude that, upon in vivo contact with bacteria such as Yersinia and Salmonella, synovial gamma delta-T lymphocytes are activated and contribute to antibacterial immunity via specific target cell lysis. Furthermore, anti-self cytolytic gamma delta-T cells could participate in the clearance of stressed and detrimental cells in the arthritic joint or, alternatively, could support the chronicity of autoimmune arthritis.

Thymoma and pure red cell aplasia in a patient with systemic lupus erythematosus

We present the case of a female patient with a diagnosis of systemic lupus erythematosus (SLE) at the age of 54 years. At the age of 63 years, she suffered from malignant thymoma and 3 years after removal of the thymoma a diagnosis of pure red cell aplasia (PRCA) was established. This is, to our knowledge, the first report of the occurrence of SLE, thymoma and PRCA in the same patient. The case is discussed with regard to the already known associations between these diseases.

Quantitative measurement of human T-cell receptor V beta subfamilies by reverse transcription-polymerase chain reaction using synthetic internal mRNA standards

Quantitative determination of T-cell receptor (TCR) V beta expression is necessary to define the changes in TCR-V beta subfamily expression that occur during T-cell maturation and selection and to detect alterations of the TCR-V beta repertoire that may be associated with human diseases. Here we describe and validate a quantitative reverse transcription-polymerase chain reaction (RT-PCR) technique to determine human TCR-V beta subfamily mRNA levels (as well as other mRNA species), based on the use of synthetic poly(A) mRNA internal standards that are coprocessed with native (sample) mRNA transcripts. The technique allows simultaneous reverse transcription of sample and standard mRNA and thus obviates errors arising during reverse transcription. In addition, the technique allows coamplification of several concentrations of standard mRNA (cDNA) with sample mRNA (cDNA) under conditions in which these mRNAs amplify with equal efficiency; thus, it avoids errors resulting from saturation of competition effects. Finally, the technique is sensitive to lower than 1.5-fold differences in input mRNA. To apply the technique, we also describe methods for the generation of poly(A) mRNA internal standards that can be used to quantitate TCR-V beta 2/6/7 and TCR-C beta mRNA.