Normal Adenosine Deaminase Research Articles

Characteristics of an aminohydrolase distinct from adenosine deaminase in cultured human lymphoblasts

An inherited deficiency of adenosine deaminase (adenosine aminohydrolase, EC 3.5.4.4) is associated with an autosomal recessive form of severe combined immunodeficiency disease. Affected patients exhibit markedly reduced or absent adenosine deaminating activity in various tissues. In this study we have demonstrated the presence of a low level aminohydrolase activity in 11 different normal and adenosine deaminase-deficient lymphoblast cell lines which is apparently distinct from normal adenosine deaminase. Based on enzymatic, physical and immunoreactive properties, this lymphoblast aminohydrolase does not appear to be related to adenosine deaminase and is most likely coded for by a different gene locus. In future investigations designed to characterize mutant forms of adenosine deaminase, it will be important to distinguish this lymphoblast aminohydrolase activity from putative products of the adenosine deaminase gene locus.

917 SEVERE COMBINED IMMUNE DEFICIENCY DISEASE – A T-CELL DISORDER

Severe combined immune deficiency disease (SCID) represents a spectrum of disorders characterized by the inability to manifest normal cell-mediated and humoral immunity. Recognition and grouping of these variants of SCID are important in order to provide guidelines for investigation and to evaluate and select appropriate therapeutic modalities. In contrast to earlier suggestions that these patients manifest abnormalities of lymphoid stem cells, our studies have demonstrated T and B-cell precursor cells in the majority of SCID patients. We have used in vitro assays for monitoring the induction of T-cell differentiation and have characterized the responsiveness of patient precursor T-cells to specific induction regimens including contact with thymic epithelium, epithelium conditioned medium, thymosin and theophylline. In this way, we have identified different groups of patients with an arrest of T-cell differentiation at different stages of maturation. In most of the patients with normal adenosine deaminase, the combined immune deficiency could be shown to reflect the failure of normal T-cell differentiation and consequent failure of T-cell dependent maturation of B lymphocytes to an antibody-secreting stage, rather than intrinsic abnormalities of the B cells themselves. These data emphasize the thymic dependence of specific B-cell differentiation in man and demonstrate the functional integrity of B lymphocytes in many patients with SCID.

963 IMMUNODEFICIENCY IN A CHILD WITH A HEALTHY ADENOSINE DEAMINASE DEFICIENT MOTHER

We recently studied a 27 year old woman with adenosine deaminase (ADA) deficiency. Red cell lysates exhibited less than 1 μmole/g hgb/hr conversion of either adenosine or deoxyadenosine to inosine. Lysates made from peripheral blood lymphocytes showed less than 0.5 nmoles/min/mg protein utilization of adenosine. Studies employing intact lymphocytes demonstrated conversion of [8-14C]-adenosine to [8-14C] inosine and [8-14C] hypoxanthine proceeded at 10-20% of the rate of normal lymphocytes. Mixing experiments with red cell extracts failed to demonstrate an inhibitor. She has produced 3 children, one of whom expired with ADA deficient severe combined immunodeficiency. This child's disease was somewhat atypical in that she had considerable lymphoid tissue and the gross and microscopic features of the thymus were relatively normal in appearance and cytology at autopsy. Her husband and 2 living children had approximately half normal ADA activity in their red cell lysates. Starch gel electrophoresis of these lysates indicated the presence of the ADA 1 phenotype. No consanguinity could be detected in the family. Although an absolute determination of the genetics of this disease in this family was not possible, the most likely explanation is that the mother is homozygous for a low activity ADA variant while the father is heterozygous for a more common form of ADA deficiency.

Adenosine deaminase deficiency: Frequency and comparative pathology in autosomally recessive severe combined immunodeficiency

Seven of thirty families with severe combined immunodeficiency (SCID) had an affected female child, which is presumptive evidence of an autosomal recessive mode of inheritance. Four of these seven families (57%) were found to carry a gene for adenosine deaminase (ADA) deficiency, in that parents and family members had ADA activity in the range of known obligate heterozygotes. In three of the four families, the diagnosis of heterozygosity for ADA deficiency was confirmed either by the subsequent birth of an affected ADA-deficient child or by testing an affected child alive following successful bone marrow transplant. In the fourth family, anomalous inheritance of the ADA genetic polymorphism confirmed the presence of a “null” allele for ADA. Thymic and bony pathology, of a type previously thought to be unique to ADA deficiency, was also found in patients with normal ADA. Retrospective diagnosis of ADA deficiency based solely upon pathologic changes is therefore not reliable.

Adenosine deaminase and nucleoside phosphorylase activity in patients with immunodeficiency syndromes

Red cell adenosine deaminase (ADA) and nucleoside phosphorylase (NP) activities were measured in 62 patients with various immunodeficiency syndromes and in 67 adult and 37 infant controls. NP activity was found to be within the normal range (1206 ± 144 U/gHb in adults, 1266 ± 270 U/gHb in infants) in all but 4 patients who had NP deficiency and abnormal T-cell but normal B-cell function. The mean ADA activity was 36 U/gHb (with 95% confidence interval of 22.5 – 58.1 U/gHb) for normal adult controls ( n = 67) and 35 U/gHb (95% confidence interval 21.6 – 60.8 U/gHb) for infant controls ( n = 37). Red blood cell ADA activity of the patients showed great variability: Normal activity was found in patients with X-linked agammaglobulinemia, ataxia telangiectasia, and Wiskott-Aldrich syndrome. Six of 17 patients with combined immunodeficiency syndrome (CID) had ADA deficiency, and 7 CID patients had significantly elevated red cell ADA activity. Two identical twins with common-variable immunodeficiency showed red cell ADA activity of five to six times that of the normal controls; however, ADA activity of white cells and cultured skin fibroblasts was normal. Family members of these twin sisters had normal red cell ADA activity. It is not known if the elevated ADA activity observed in some patients with immune deficiency is directly related to the abnormal immune function.

Allergy and Immunology: An Annotated Bibliography of Recent Literature

Allergy and Immunology: An Annotated Bibliography of Recent Literature

Overproduction of adenine deoxynucleosides and deoxynucletides in adenosine deaminase deficiency with severe combined immunodeficiency disease.

The deoxynucleotide, dATP, is elevated 50- to 1,000-fold above normal in erythrocytes, lymphocytes, and bone marrow from a child with adenosine deaminase deficiency and severe combined immunodeficiency disease. The child, when 17 mo of age, was also excreting approximately 30 mg of deoxyadenosine per day in urine (normal is less than 0.1 mg/day). Urinary excretion of uric acid was decreased. Elevated dATP levels in lymphocytes and bone marrow, and increased urinary excretion of deoxyadenosine, persisted despite hypertransfusion of the child with irradiated erythrocytes from a donor with normal adenosine deaminase. Overproduction of deoxynucleotides by increased salvage of adenosine appears to be the primary metabolic abnormality in patients with adenosine de aminase deficiency.

The effect of adenosine on mitogenesis of ADA-deficient lymphocytes

We have determined the effects of adenosine on intrinsically adenosine deaminase-deficient lymphocytes. These cells are circulating peripheral lymphocytes from a patient with T-cell immunodeficiency. The patient has been successfully treated with normal red cell transfusions. The lymphocytes contain about 8% of the normal adenosine deaminase level. Mitogen response is nearly normal but is inhibited by adenosine at one tenth the level required for inhibition of normal lymphocytes. Determination of the disappearance of exogenously added adenosine to lymphocytes cultured in horse serum suggest that (1) ADA-deficient cells are more sensitive to adenosine toxicity because of an impaired ability to deaminate adenosine and (2) that adenosine inhibits mitogenesis only if it is present during the first 24 hr of mitogen stimulation.

687 ADENOSINE DEAMINASE DEFICIENICY WITHOUT IMMUNODEFICIENCY

A 20 month old male child was diagnosed as having adenosine deaminase (ADA) deficiency during N.Y. State-mandated neonatal screening. At age one month he had tonsils, a normal WBC and differential, a thymic shadow, and normal bony structures, despite confirmation of his enzyme defect on repeated testing (less than 1% of normal ADA and increased adenosine in RBC). Throughout his life he has had normal numbers and distribution of lymphocytes, normal responses to pokeweed mitogen, phytohem-agglutinin, and Con A, and a normal mixed lymphocyte reaction. Following immunization he developed antibody and/or positive in vitro responses to diptheria, tetanus, and polio antigens. Skin tests with DNCB and diptheria toxoid yielded delayed hypersensitivity responses. Except for accentuated transient physiologic hypogammaglobulinemia, he has had normal immunoglobulins and complement. Except for several brief episodes of otitis media and an upper respiratory infection his general health has been excellent, and his growth and development have been normal. Genetic heterogeneity for ADA deficiency may account for the spectrum of clinical manifestations, ranging from Severe Combined Immunodeficiency to normal immunologic function.

TISSUE ADENOSINE DEAMINASE ACTIVITY IN AN ADENOSINE DEFICIENT-COMBINED IMMUNODEFICIENCY DISEASE PATIENT

Patients with combined immunodeficiency (CID) and adenosine deaminase (ADA) deficiency may have low or absent ADA activity in various tissues. Hirschhorn et al. have shown that the activity in patient fibroblasts is a mutant form of ADA (PNAS 73: 213, 1976). Others have suggested that the deficiency reflects an inhibition of ADA (Trotta et al., PNAS 73: 104, 1976). We have isolated and in part characterized properties of the residual ADA from spleen of one patient. Radioimmunoassay for ADA protein in erythrocytes and spleen extracts of the patient showed no cross-reacting protein. Chromatography of ADA-CID spleen extracts produced a fraction with adenosine deaminating activity which could not be adsorbed on affinity or anti-ADA columns. The deaminating activity could not be inhibited with erythro-9-(2-hydroxyl-3-nonyl) adenosine. The pH optimum activity curve and Km differed from normal spleen ADA. A similar fraction, representing about 1% of the total ADA activity, was isolated from normal spleen extracts. We conclude that the adenosine deaminating activity observed in patients with ADA-CID is not ADA. The activity may be due to an enzyme whose principal substrate may be another metabolite. The presence of this non-ADA deaminating activity in normal spleen suggests that the observed activity in ADA-CID tissue is not due to a mutant form of ADA and that the inhibited enzyme activity reported by Trotta et al. may be due to an amplification of this non-ADA deaminating enzyme.