T-cell receptor Valpha gene expression of infiltrating T cells in pancreatic cancer

T cell receptor β-chain repertoire analysis of tumor-infiltrating lymphocytes in pancreatic cancer

Pancreatic cancer is lethal due to lack of perceptible symptoms and effective treatment methods. Immunotherapy may provide promising therapeutic choices for malignant tumors like pancreatic cancer. Tumor‐infiltrating lymphocytes (TIL) in tumor mesenchyme could recognize peptide antigens presented on the surface of tumor cells. The present study aimed to test the relationship between the T cell receptor (TCR) β repertoire of the tumor and peripheral blood, and also to investigate the intra‐tumor spatial heterogeneity of the TCR β repertoire in pancreatic cancer. To the best of our knowledge, this is the first study to evaluate the clonal composition of TCR β repertoire in TIL across the spatial extent of pancreatic cancer. In this study, we studied 5 patients who were diagnosed with primary pancreatic cancer. Ultra‐deep sequencing was used to assess the rearrangement of the TCR β‐chain (TCR β) gene. HE staining and immunohistochemistry of CD3, CD4, CD8 and HLA class I were used to show histopathology and immune conditions macroscopically. TIL repertoire showed that different regions of the same tumor showed a greater number of repertoire overlaps between each other than between peripheral blood, which suggested that T cell clones in pancreatic cancer might be quite different from those in peripheral blood. In contrast, intra‐tumoral TCR β repertoires were spatially homogeneous between different regions of a single tumor tissue. Based on these results, we speculated that the cellular adaptive immune response in pancreatic cancer was spatially homogeneous; this may pave the way for immunotherapy for the treatment of pancreatic cancer patients.

Distributional and functional alterations of immunocompetent peripheral blood lymphocytes in patients with chronic pancreatitis

OBJECTIVE

To investigate whether the chronic inflammatory process in patients with chronic pancreatitis affects their immune function.

SUMMARY BACKGROUND DATA

Chronic pancreatitis is a chronic inflammatory disease of the exocrine pancreas. In approximately 30% of patients, an inflammatory mass of the pancreatic head is found, representing an indication for surgery.

METHODS

This study comprised 28 patients with chronic pancreatitis. Sixteen patients were also reevaluated 1 year after resection of the pancreatic head for chronic pancreatitis.

RESULTS

Compared with an age- and gender-matched control group, the number of CD3(+) cells was significantly increased in patients with chronic pancreatitis, with an increase of both CD3(+)CD4(+) and CD3(+)CD8(+) cells. The number of natural killer cells or B lymphocytes did not differ between the patients and the control group. After stimulation with phytohemagglutinin or anti-CD3 antibodies, the blastogenic response was significantly attenuated in the patients with chronic pancreatitis. One year after resection of the pancreatic head for chronic pancreatitis, the distribution and the blastogenic response to phytohemagglutinin and anti-CD3 antibodies had returned to normal compared with preoperative values.

CONCLUSION

The chronic inflammatory process in chronic pancreatitis markedly affects the distribution and function of peripheral immunocompetent blood cells, and elimination of the chronic inflammatory focus by pancreatic head resection restores the suppressed immune function in these patients.

Pseudo-spikes are common in histologically benign lymphoid tissues

T cell receptor gene rearrangement is a classic marker of T cell clonality and is a useful adjunct in the diagnosis of T cell lymphomas and leukemias. Rearranged V-J gene segments amplified by polymerase chain reaction (PCR) are traditionally analyzed by polyacrylamide gel electrophoresis. We and others have analyzed TCR-gamma PCR products using capillary gel electrophoresis, which produces single nucleotide resolution and provides improved diagnostic sensitivity over conventional methods. However, with this marked increase in resolution and sensitivity, it is necessary to re-define normal variation of TCR-gamma gene rearrangement in control tissues to allow appropriate interpretation of monoclonality if present. Using DNA capillary gel electrophoresis, we examined the spectrum of normal patterns for TCR-gamma in a variety of T-cell-rich, histologically benign tissue types, including spleen, lymph node, tonsil, and blood, and compared this with the patterns in T cell lymphoma samples. We defined relative peak heights as h1/h2, where h1 represents the peak height of the largest peak above the normally distributed population, and h2 represents the peak height of the normally distributed curve. We found spikes in almost 20% of histologically benign samples with relative peak heights that were more than 0.5 and up to 1.5. We designated these as pseudo-spikes, because they may be mistaken for monoclonal spikes. In contrast, the relative peak height of the T cell lymphoma samples that showed clonal rearrangement was much higher than that of the pseudo-spikes, being at least 2 in 11/11 and at least 3 in 10/11 cases. Our data suggest that peaks with relative height of at least 3 represent a true clonal population in diagnostic samples. Peaks with relative heights of less than 1.5 may be insignificant, while peaks with relative heights between 1.5 to 3 may warrant further evaluation. Although capillary gel electrophoresis is superior in assessing T cell clonality, caution must be exercised when interpreting results, because pseudo-spikes appear to be common in benign tissues with lymphoid populations and are not necessarily indicative of clonal malignant T cell population.