Adenosine deaminase (ADA) activity is increased in effusions caused from certain clinical conditions including tuberculosis and bacterial infections.

Adenosine deaminase (ADA) activity is increased in effusions caused from certain clinical conditions including tuberculosis and bacterial infections. In this cogitation the ADA isoenzyme patterns in tuberculous and parainfective effusions were investigated to determine the isoenzyme responsible for this increase in activity. Fifty-one tuberculous effusions and six parainfective effusions were investigated. All effusions had increased ADA activity (median values of 126 and 127 units/L, respectively). In the tuberculous effusions, [ADA.sub.2] isoenzyme was raise to be primarily responsible for total activity, with a median contribution of 88 percent The [ADA.sub.1] (both [ADA.sub.1m] and [ADA.sub.1c] isoenzymes) was the major isoenzyme in the parainfective effusions with a median contribution of 70 percent The [ADA.sub.2] isoenzyme activity greatest in number likely reflects monocyte-macrophage turnover or activity, while [ADA.sub.1] probably originates from lymphocyte or neutrophils. It is therefore essential to determine the isoenzyme profile when interpreting ADA activity evens in effusions. The measurement of the individual isoenzymes will enhance the diagnostic utility of ADA activity determinations in pleural effusions.

(Chest 1994; 106:33-37)

ADA = adenosine deaminase (including all isoenzymes)

Adenosine deaminase (ADA [EC 3544]) catalyzes the deamination of adenosine and deoxyadenosine to inosine and deoxyinosine, respectively. pair isoenzymes of ADA coded by way of different gene loci exist, namely [ADA.sub.1] and [ADA.sub.2], each with unique biochemical properties.(1) The [ADA.sub.1] isoenzyme is originate as a monomer ([ADA.sub.1m]) and as a dimer ([ADA.sub.1c]), where pair [ADA.sub.1m] molecules are combined with a combining protein.(1) The [ADA.sub.1] isoenzymes are fix in all cells, with the highest activity in lymphocyte and monocytes, whereas [ADA.sub.2] isoenzyme gene produces appear to be found simply in monocytes.(2) The assay of ADA activity in pleural and other effusions is self-same useful in differential diagnosis, especially in the case of tuberculosis, which is characterized by means of an increase in activity.(3)(4)(5)(6)(7)

Because of the unique distribution and characteristics of the ADA isoenzymes, it is essential for interpretation of terminates to determine the contribution of each to the total activity. The orders used to distinguish between the sum of two units isoenzymes are generally based upon the ratio of activity, using the sum of two units substrates adenosine and deoxyadenosine, respectively.(8)(9) These examples are, however, only an approximation of the real isoenzyme pattern, and cannot distinguish between [ADA.sub.1m] and [ADA.sub.1c].

In this meditation the composition of the ADA enzyme in tuberculous effusions was investigated. The effusions were for the greatest part of pleural origin, but a not many cases of ascites were included. A small number of parainfective and empyemic effusions, characterized at an increased ADA activity, also were examined. brace techniques, one a spectrophotometric and the other an electrophoretic mode were used to determine the activity of the isoenzymes. The correlation between the couple methods also is discussed.

PATIENTS AND METHODS

Forty-one tuberculous and ten ascites effusions from patients with confirmed tuberculosis were examined. All of these patients were of African declivity 30 men and 21 women Their median age was 41 years, ranging from 19 to 107 years. The tuberculosis diagnosis was based in succession standard criteria which included clinical findings, x-ray film examinations, histologic findings, cytologic features, and agricultures for Mycobacterium tuberculosis. Tuberculous ascites have the same characteristics relating to ADA activity as pleural effusions,(6) and no difference between the pair origins of effusions could be lay opened in our study. Therefore, we have disposeed the tuberculous effusions together, irrespective of the origin. Parainfective pleural effusions (including empyema) with increased ADA activity also were studied in six patients. sum of two units of these patients were of African and four of European descent; five were men and undivided woman. Their median age was 25 years, ranging from 13 to 43 years. Increased ADA activity was defined as of the same heights above 35 unit/L. This even generally has been found to be the optimum cutoff flush to distinguish between tuberculous effusions (high activity) and other effusions.(4)(6) All the effusions studied had increased ADA activity.

The total ADA activity was determined by way of the spectrophotometric method described on Giusti and Galanti.(10) Adenosine was used as substrate and the amount of ammonia formed was measured by way of Berthelot's reaction. To distinguish between the [ADA.sub.1] and the [ADA.sub.2] forms, the ADA activity was measured using the same technique with and without erythro-9-(2-hydroxy-3-nonyl) adenine. Erythro-9-(2-hydroxy-3-nonyl) adenine is a influential inhibitor of only [ADA.sub.1] isoenzymes and a concentration of 200 [micro]mol/L was used in the reaction solution.(11) In its vicinity only the [ADA.sub.2] isoenzyme is active. The [ADA.sub.1] activity is then calculated by the agency of subtracting the [ADA.sub.2] isoenzyme activity from total ADA activity. This rule however, cannot differentiate between [ADA.sub.1m] and [ADA.sub.1c].

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