Combined immunodeficiency and inborn errors of purine metabolism

Liver purine nucleoside phosphorylase in Camelus dromedarius: purification and properties

1. Purine nucleoside phosphorylase (purine nucleoside:orthophosphate ribosyl transferase, EC 2.4.2.1) was purified to electrophoretic homogeneity from the liver of Camelus dromedarius. 2. The enzyme appears to be a dimer with a 44,000 subunit mol. wt and displays non-linear kinetics with concave downward curvature in double reciprocal plots with respect to both inosine and orthophosphate as variable substrates. 3. The effect of thiol compounds on the enzyme activity and of pH on kinetic parameters is reported.

C-reactive protein, sialic acid and adenosine deaminase levels in serum and pleural fluid from patients with pleural effusion

Laboratory analysis of pleural fluids is essential to determine underlying diseases. The authors evaluated the clinical significance of C-reactive protein (C-RP), sialic acid (SA), and adenosine deaminase (ADA) determinations in sera and pleural fluids from 37 patients with pleural effusion. (FP12)C-RP and sialic acid levels and ADA activities were higher in exudates than in transudates of pleural fluids. Serum and pleural fluid C-RP levels were high in patients with pyothorax. Determinations of serum sialic acid and the pleural fluid to serum ratio were useful for the differential diagnosis of pulmonary tuberculosis and malignancy. ADA activities of pleural fluid and serum are useful for the differentiation of malignancy from tuberculosis and nonspecific pyothorax. C-RP concentrations of pleural fluid correlated to serum levels. However, concentrations of sialic acid and ADA activities were not correlated to serum levels and only correlated to protein concentrations of pleural fluids.

Morphology of original and transplanted thymuses in severe combined immunodeficiency

Twenty-six patients with severe combined immunodeficiency (SCID) were examined. In 20 cases no defect of the biochemical pathways was found; 6 cases showed a deficiency in adenosine deaminase (ADA) activity. In 19 cases histological sections of the thymus were available. In 3 cases, in addition to the original thymuses, transplanted thymic allografts were microscopically examined. The thymus in SCID without abnormality of the ADA pathway showed a uniform dysplastic pattern with only moderate variations related to mode of inheritance and length of survival. The thymus in SCID with ADA deficiency displayed a heterogeneous pattern ranging from almost normal to a completely dysplastic structure, whereas the transplanted thymic allografts presented either a normal or a dysplastic appearance. The morphology of the thymus is not pathognomonic of any given biochemical defect, clinical course, or type of SCID. SCID with apparently normal biochemical pathways probably results from a variety of pathogenetic mechanisms.

Purine metabolic enzymes in lymphocytes. IV. Effects of enzyme inhibitors and enzyme substrates on the blastogenic responses of human lymphocytes

Coformycin, which is an inhibitor of adenosine deaminase, significantly inhibited in vitro blastogenic responses of human lymphocytes to both phytohaemagglutinin (PHA) and pokeweed mitogen (PWM), whereas blastogenic responses to bacterial lipopolysaccharide (LPS) were rather enhanced by the addition of coformycin. Blastogenic responses of lymphocytes to PHA and PWM were markedly suppressed by the addition of adenosine, which is a substrate of adenosine deaminase. Allopurinol, which is an inhibitor of xanthine oxidase, inhibited blastogenic responses of human lymphocytes to PHA, PWM, and bacterial LPS. Inosine (a substrate of purine nucleoside phosphorylase) and hypoxanthine (a substrate of xanthine oxidase) showed no or only a small effect on blastogenic responses of human lymphocytes. These results suggest that adenosine deaminase activity is associated with the T-cell response but not with the B-cell response and that the impaired T-cell response in adenosine deaminase deficiency is the result of intracellular retention of adenosine in T cells. The results also suggest that purine nucleoside phosphorylase or xanthine oxidase activity is associated with both T- and B-cell responses.

Severe combined immunodeficiency disease: a pathological analysis of 26 cases

Autopsy material and clinical information were analyzed in 25 cases of untreated or unsuccessfully treated severe combined immunodeficiency disease and one case successfully treated by bone marrow grafting. Two cases were adenosine deaminase deficient and one was nucleoside phosphorylase deficient. The histological appearance of the thymus fell into four clearly recognizable patterns: simple dysplasia, dysplasia with corticomedullary differentiation, dysplasia with pseudoglandular appearance, and atrophic pattern. Three cases lacked lymph nodes and belonged to the category of thymic dysplasia with pseudoglandular appearance. From the data, the following conclusions can be made: (i) The thymic atrophic pattern is a phase in a dynamic process of which the end result is simple dysplasia or dysplasia with corticomedullary differentiation. (ii) The pseudoglandular pattern represents a disease process of early intrauterine onset. (iii) At least a proportion of the cases represent a T-cell defect rather than a lymphoid stem-cell defect. (iv) The lymphoid germinal centers are not the source of plasma cells. (v) The graft-versus-host reaction probably causes lymphoid cells depletion in lymph nodes and spleen.

Therapy in adenosine deaminase and purine nucleoside phosphorylase deficient patients

The discovery of the causal association of adenosine deaminase (ADA) and purine nucleoside phosphorylase (PNP) deficiency with some forms of primary immunodeficiency disease had led to new approaches to therapy, such as enzyme replacement. In ADA deficiency, bone marrow transplantation remains the primary method of choice. If no suitable bone marrow donor is available, enzyme replacement with irradiated erythrocyte transfusions should be considered. The latter therapy may be sustained by treatment with thymic factors. In ADA deficiency, bone marrow transplantation and, in about 50% of the cases, also enzyme replacement, may result in clinical and neurological improvement with concurrent (partial) restoration of immune function and (partial) disappearance of the metabolic abnormalities present before treatment. In PNP deficiency, enzyme replacement has been evaluated carefully in only two patients. The results disclose profound changes in the purine excretion patterns after each transfusion, and a slow but partial restoration of in vitro T cell function. Treatment of ADA and PNP deficiency with continued enzyme replacement by erythrocyte transfusions has certain risks which hopefully can be overcome in the near future by loading the patient's own blood cells with the missing enzyme.

Purine metabolism in relation to leukemia and lymphoid cell differentiation

A number of inborn errors of purine metabolism have been associated with immunodeficiency diseases. From studies to the possible mechanism(s) leading to the defects in the immune system, it appeared that the accumulation of deoxyATP and deoxyGTP and the subsequent inhibition of ribonucleotide reductase played an important role. The inhibition of methylation pathways through the accumulation of s-adenosylmethionine seems to be a second valid concept. The amount to which certain subtypes of lymphoid cells were affected by the enzyme deficiencies was strongly related to the enzymatic make-up of the cells. Lymphoid cells from different maturation stages could be affected in a specific way, depending on the different enzyme activities of these cells. Studies on human lymphoblastic leukemias showed that, related to the immunological subtype, the different leukemias could be characterized by a different enzymatic make-up. In this paper we discuss the possibilities for a specific enzyme directed chemotherapy, directed against specific subtypes of human lymphoblastic leukemias. Experimental evidence indicates that for example the adenosine deaminase inhibitor 2'deoxycoformycin can be used as a specific drug against acute lymphoblastic leukemia with the T cell phenotype.

HPLC analysis of aromatic amino acids, nucleosides, and bases in plasma of acute lymphocytic leukemia on chemotherapy

Plasma chromatograms--obtained by the reversed-phase mode of high performance liquid chromatography (HPLC)--of 19 subjects with acute lymphocytic leukemia (ALL) were compared to those of 19 normal individuals. ALL patients were in remission and on a methotrexate and 6-mercaptopurine maintenance regimen. The concentrations of the aromatic amino acids L-phenylalanine and L-tyrosine, the nucleosides uridine, adenosine, inosine, and guanosine, as well as the bases hypoxanthine and xanthine, were elevated in the leukemic in comparison to the normal chromatograms. Highest inosine levels corresponded to leukemic subjects whose condition severely deteriorated with time. Patients with lower inosine levels are still in continuous remission.

Alterations in nucleotide content of human lung fibroblasts infected with Mycoplasma pneumoniae

The nucleotide content of normal MRC-5 human lung fibroblasts and fibroblasts infected with Mycoplasma pneumoniae PI 1428 was determined. Nucleotides from control and infected fibroblasts were extracted with 5% trichloracetic acid. After neutralization of the extracts, the nucleotides in the extracts were separated by anion-exchange chromatography. Significant differences were found between the nucleotide content of the control and infected cells. Nucleotide triphosphate levels were twofold higher in the control fibroblasts than in the infected fibroblasts 4 h after the initiation of infection. At the same time, nucleotide diphosphate and monophosphate levels were higher in the infected fibroblasts than in the control fibroblasts. Determination of the energy charge ratio for each set of nucleotides (adenosine, guanosine, cytidine, and uridine) demonstrated a shift of nucleotide content in the infected fibroblasts. Immediately after infection, the energy charge for each set of nucleotides was higher for the control fibroblasts than it was for the infected fibroblasts. This pattern continued throughout the infection period with only minor exceptions. The work presented here indicates a loss of energy charge in fibroblasts infected with M. pneumoniae and may help to explain some of the metabolic changes and cell damage which accompany infection.

Purine metabolic enzymes in lymphocytes. II. Adenosine deaminase and purine nucleoside phosphorylase activities in the immune response

ICR mice were immunized with sheep red blood cells (sRBC). Both adenosine deaminase (ADA) and purine nucleoside phosphorylase (PNP) activities in spleen lymphocytes increased faster than the serum antibody titer and reached a peak one week after the immunization. ADA activity increased significantly in T lymphocytes but not in B lymphocytes collected from the spleens of the immunized mice. A statistically significant increase in PNP activity was found in both T and B lymphocytes from the spleens of the immunized mice. Spleen lymphocytes collected from ICR mice which had been immunized with mitomycin C-treated sarcoma 180 (S180) cells one week earlier showed cytotoxic activity against viable S180 cells. Both ADA and PNP activities in spleen lymphocytes of S180-immunized mice increased significantly, and both activities increased in T lymphocytes prepared from spleen of immunized mice. In contrast, an increase was found in PNP activity but not in ADA activity in B lymphocytes. These results suggest that an increase in both ADA and PNP activities may by necessary for the T-cell response in both humoral and cellular immune responses, and that an increase in PNP activity may be necessary for the B-cell response.

Purine metabolic enzymes in lymphocytes. I. Adenosine deaminase and purine nucleoside phosphorylase activities in mouse lymphocyte subpopulations

The distribution of adenosine deaminase (ADA) and purine nucleoside phosphorylase (PNP) activities in lymphoid organs and lymphocyte subpopulations in mice, and the effect of phytohemagglutinin P (PHA-P) and concanavalin A (Con A) on the enzyme activities were studied. ADA activity was distributed equally in cells from all organs used and no mouse strain differences were observed. In contrast, PNP activity varied with the mouse strain, being highest in C57BL/6 mice and lowest in BALB/c mice, and with the organ in ICR mice, being high in peripheral blood lymphocytes and spleen lymphocytes, low in mesenteric lymph node cells and absent or very weak in thymus cells. T and B lymphocytes were prepared from spleen of ICR mice. High ADA activity was found in both T and B lymphocytes, whereas PNP activity in the T lymphocytes was about one-third of that in the B lymphocytes. PNP activity in thymus cells was increased to the normal level of T lymphocytes in the spleens by cultivation without stimulant. The development of PNP activity in thymus cells was partially inhibited by Con A but was not affected by PHA-P. ADA activity in thymus cells was enhanced by in vitro stimulation with PHA-P but not with Con A. In contrast, in spleen lymphocytes the development of ADA activity was enhanced by stimulation with PHA-P and Con A, and that of PNP activity was enhanced by PHA-P but not by Con A.

Biochemical and functional abnormalities in lymphocytes from an adenosine deaminase-deficient patient during enzyme replacement therapy

Biochemical and immunological properties of lymphocytes were measured repetitively over a period of 40 mo during enzyme replacement by transfusion in a child with adenosine deaminase (ADA) deficiency and severe combined immunodeficiency disease. Catalytically defective ADA protein is present in the child's cells. ADA activity in his lymphocytes is 7 nmol/min per 10(8) cells with 51 ng of ADA protein/10(8) cells by radioimmunoassay. ADA activities in normal cord and adult lymphocytes average 193 and 92 nmol/min per 10(8) cells, respectively, with 429 and 223 ng of ADA protein/10(8) cells. Deoxy(d)ATP accumulates in the patient's erythrocytes and lymphocytes. Transfusion of irradiated packed erythrocytes partially corrects the metabolic defects. Frank metabolic relapse occurs if transfusions are discontinued for several months. The amounts of dATP in erythrocytes and lymphocytes averaged 13 and 2 times normal, respectively, during periods when transfusions were administered every 2-4 wk. Deoxyguanosine triphosphate and deoxycytidine triphosphate in lymphocytes were normal on 11 occasions, but deoxyribosylthymine triphosphate was ninefold increased. On 11 occasions dATP was measured in lymphocytes and erythrocytes isolated simultaneously. There was a positive, but statistically insignificant, correlation between amounts of dATP in the two types of cells (r = 0.25,P > 0.1). The absolute peripheral lymphocyte count was correlated with the activity of ADA in circulating erythrocytes and with the response of lymphocytes to phytohemagglutinin (r = 0.64, P < 0.01; r = 0.49, P < 0.05). Response of lymphocytes to stimulation by phytohemagglutinin in vitro and absolute peripheral lymphocyte counts were not significantly correlated with levels of dATP in the erythrocyte or lymphocyte during periods of intensive therapy. Although there was objective improvement during enzyme replacement, the child remained immunodeficient and biochemically abnormal.

T system immunodeficiencies in infancy and childhood

Some problems concerning the diseases due to deficiencies of the T immune system in infancy and childhood are reviewed. The relationships between SCID and Nezelof syndrome and the pathogenesis of this group of diseases are particularly discussed.