Immunohistochemical localization of adenosine deaminase in human benign extrathymic lymphoid tissues and B-cell lymphomas

Purinergic signalling and cancer

Receptors for extracellular nucleotides are widely expressed by mammalian cells. They mediate a large array of responses ranging from growth stimulation to apoptosis, from chemotaxis to cell differentiation and from nociception to cytokine release, as well as neurotransmission. Pharma industry is involved in the development and clinical testing of drugs selectively targeting the different P1 nucleoside and P2 nucleotide receptor subtypes. As described in detail in the present review, P2 receptors are expressed by all tumours, in some cases to a very high level. Activation or inhibition of selected P2 receptor subtypes brings about cancer cell death or growth inhibition. The field has been largely neglected by current research in oncology, yet the evidence presented in this review, most of which is based on in vitro studies, although with a limited amount from in vivo experiments and human studies, warrants further efforts to explore the therapeutic potential of purinoceptor targeting in cancer.

The B cell, arthritis, and the sympathetic nervous system

The pathogenesis of rheumatoid arthritis (RA) is still an unresolved puzzle. Many factors and inflammatory cells play together to initiate a chronic inflammatory process that, if untreated, leads to complete destruction of involved joints. Recent success in treating severe forms of RA with B cell-depleting or -modifying agents revived the concept that the B cell might play a pivotal role in the pathogenesis of some forms of arthritis. However, the rather unspecific treatment approach affecting all B cells, no matter if autoreactive or not, leads to potential harmful side-effects, e.g., severe infections. Therefore, finding regulatory systems that more specifically modulate B cell function is important to improve current treatment options. One such regulatory system is the sympathetic nervous system (SNS), which is known to modulate B cell function, but also profoundly influences arthritis development and severity. This review develops the hypothesis that the SNS via modulating B cell function influences arthritis development and progression. For this purpose data is presented that shows (1) how the SNS influences B cell function, (2) how the SNS influences arthritis development and severity, and (3) how B cells are involved in the disease process with an emphasis on possible contact points for SNS neuromodulation.

Anti-adenosine deaminase antibodies in lupus erythematosus

Adenosine deaminase (ADA) is an enzyme involved in purine metabolism and has a major role in the development and function of lymphoid cells. Congenital deficiency of ADA results in severe immunodeficiency. Patients with congenital ADA deficiency treated with polyethylene glycol-conjugated bovine ADA develop antibodies to ADA. This leads us to investigate the role of anti-ADA antibodies in patients with systemic rheumatic diseases. Commercially available ADA was used in ELISA and immunoblots for detection of anti-ADA antibodies. Four out of 100 patients examined were positive for anti-ADA antibodies. Two of them had peripheral blood lymphopenia but the antibody levels did not appear to correlate with the lymphocyte counts. Immunoblotting revealed that the antibodies recognized a 40 kDa peptide of ADA, corresponding to ADA1, the major component of ADA. Affinity-purified antibodies were used to locate the distribution of ADA on Hep-2 cells and lymphocytes by indirect immunofluorescence. Anti-ADA antibodies gave a distinct nuclear speckled pattern on acetone-fixed cells. With viable cell immunofluorescence, anti-ADA antibodies also stained the cell surface of HEp-2 cells and lymphocytes, indicating surface expression of ADA. The anti-ADA antibodies failed to gain access into the cytoplasm or nuclei when added to the cultures of HEp-2 cells. In summary, this is the first report of detection of anti-ADA1 autoantibody which is a new type of ANA with discrete, speckled nuclear staining, but which may not be associated with lymphopenia.

Markers of T-cell differentiation and maturation in C57BL/6 and BALB/c mice and in the calf: a comparative study

No significant differences were found between C57BL/6 and BALB/c mice in the levels of Thy 1.2 antigen (a T-cell marker) or the activities of the T-cell maturation-related enzymes adenosine deaminase (ADA, EC 3.5.4.4), serine-esterase (SE, EC 3.4.21), N-acetyl-beta-D-glucosaminidase (NABG, EC 3.2.1.30) and beta-glucuronidase (BG, EC 3.1.1.1), in either unfractionated lymphoid cells or T-lymphocyte-enriched fractions. ADA, SE, NABG and BG activities were much higher (P < 0.01) in the calf than in the corresponding populations in mice. However, the distributions of these activities among thymocyte subpopulations were very similar in mice and the calf. These results provide indirect evidence to suggest that the course of T-cell maturation is similar in mice and the calf.

DNA synthesis and nucleoside metabolism in human tonsillar lymphocyte subpopulations

High (HD) and low (LD) density cells were separated on 25% BSA gradient from tonsils of 3-6 years old children. Early B lymphocyte markers and sIg-s were found on the surface of 59-82% of the LD cells. This cell population was 5-6 times more active in DNA synthesis (3H-thymidine incorporation, DNA polymerase activity) than the HD cells. The total uptake of 3H-deoxycytidine was about the same as that of 3H-thymidine. As long as practically all thymidine taken up by the cells was immediately incorporated into DNA (90-95%), only 10-15% of deoxycytidine was incorporated into DNA under the same conditions, indicating different pool sizes for the DNA precursors. The majority of deoxycytidine (70%) was converted and incorporated as dTMP. A considerable part of labeled deoxycytidine could be detected in the soluble pool in form of nucleotides (3-8%), and in an unknown form, called substance X (8-14%). Substance X was purified by TL chromatography and identified by HPLC as deoxycytidine containing liponucleotides, probable precursors for plasmamembranes. The preferential utilisation of deoxycytidine for DNA and membrane synthesis in immature B lymphocytes draws the attention to its function in early events of lymphocyte maturation.

Adenosine deaminase and terminal deoxynucleotidyl transferase in human lymphomas: an aid to the diagnosis and subclassification of lymphoblastic lymphomas

Adenosine deaminase (ADA) and terminal deoxynucleotidyl transferase (TdT) activities were determined on 97 biopsy specimens obtained from patients with non-neoplastic diseases (12 cases), Hodgkin (30 cases), and non-Hodgkin lymphomas (55 cases). Thirty additional cases were tested only for TdT. TdT was positive in 10 out of 13 lymphoblastic lymphomas (LL) examined and negative in all the other specimens, including the ten cases of the immunoblastic type. Levels of ADA above 350 U/mg of protein were found in 10 out of 12 LL tested, but not in any other specimen. The 3 TdT- LL had high contents of ADA. Therefore, all LL can be detected using both ADA and TdT markers. The 3 TdT- LL had a heterogeneous phenotype and their possible origin is discussed in view of the possibility that they constitute a rare entity distinct from the more common TdT+ LL. Very low levels of ADA (below 100 U/mg of protein) were found in chronic lymphocytic leukemia and immunocytoma, and in Burkitt's lymphoma. In other B-cell non-Hodgkin lymphomas, intermediate values between 100 and 350 U were often found, and this finding could be relevant to the different cellular origin of the various B-cell neoplasias. We conclude that ADA distribution is solid lymphoid tumors reflects the cellular origin of these neoplasias. Adenosine deaminase alone and in combination with TdT can be useful in the diagnosis and classification of childhood lymphomas in which the immature hystotypes predominate.

A flow cytometric method for the detection of adenosine deaminase in mononuclear cells

The purpose of this study was to develop a flow cytometric method for the detection of adenosine deaminase (ADA) in a single cell suspension of mononuclear cells. Anti-human ADA antibody was purified by affinity chromatography on a column of Sepharose 4B to which calf ADA was covalently linked. This antibody was used for indirect immunofluorescent staining of cells fixed in 4% paraformaldehyde. The specificity of staining was proved by substitution of anti-human ADA with normal rabbit IgG and by absorption experiments. The fluorescence profile of the cells was then analyzed by flow cytometry. Two groups of cells were studied: (a) thymocytes, tonsil cells and peripheral blood mononuclear cells (PBMC), (b) ADA-positive and ADA-deficient cell lines. In each of these populations of cells a peak of specific immunofluorescence staining for the enzyme could be easily distinguished from weak background staining of control preparations. Within each group, the cell population with higher ADA activity also displayed a greater intensity of cell fluorescence. Flow cytometry provides a means for quantitation of ADA in individual mononuclear cells.

Immunomorphological localization of adenosine deaminase in rat tissues during ontogeny

Immunomorphological methods were used to localize adenosine deaminase in tissues of the rat at different stages of ontogeny. In the thymus, lymphocytes began to express significant amounts of the enzyme with the appearance of demarcation between the cortex and medulla at 17 days of gestation. At any stage of ontogeny studied, strong adenosine deaminase staining was seen predominantly in cortical thymocytes. In the spleen and lymph node, the enzyme was initially detected in T cell areas, whereas primary follicles did not show positive adenosine deaminase staining. During further development, the enzyme was demonstrated in some lymphocytes of germinal centres and plasma cells. In the duodenum, epithelial cells of villi and the neck of crypts showed positive adenosine deaminase staining whereas no staining for the enzyme was observed in the epithelial cells of the base of crypts. Strongly positive staining for adenosine deaminase appeared in plasma cells of the lamina propria by four weeks after birth. The transient positive reaction for the deaminase could be recognized in epithelial cells of tubules of the kidney during late foetal and early postnatal development. The tubules of adult rats did not stain for the enzyme. In the cartilage of 15-day foetuses, positive adenosine deaminase staining was seen only in perichondrial cells and hypertrophic cells. Kupffer cells in the liver and endothelial cells of blood vessels stained positively for the enzyme at every stage of ontogeny studied.