Adenosine deaminase levels in cerebrospinal fluid in tuberculosis and bacterial meningitis

Detection of antigen and antibody in childhood tuberculous meningitis

OBJECTIVE

Mycobacterium tuberculosis excretory secretory 31 kDa, a serine protease antigen (M. tb ES-31), prepared from Mycobacterium tuberculosis H37Ra culture medium has been shown to have potential in detecting tuberculosis. Precise diagnosis and management of tuberculous meningitis, in children in particular, is essential to curtail mortality and morbidity.

METHODS

In this study, M. tb ES-31 antigen, was used in Indirect ELISA to detect tuberculous IgG antibody, in sera and CSF samples while affinity purified anti ES-31 goat antibody was used in sandwich ELISA for detection of tuberculous antigen. In sixty-five samples each of CSF and sera from cases with neurotuberculosis and control with non-tuberculous diseases were collected from Kasturba Hospital, Sevagram.

RESULTS

Among the 20 patients suffering from neurotuberculosis the IgG antibody was detected in 17(85%) of CSF and 16(80%) of sera samples, while antigen was detected in 18 (90%) in CSF and 16 (80%) in sera. Overall specificity of the assay for both IgG antibody and antigen detection in CSF was 96% while in sera it was 94% for IgG antibody and 96% for antigen detection.

CONCLUSION

This study showed the usefulness of mycobacterial serine protease antigen and its antibody in detecting neurotuberculosis.

The possible role of cerebrospinal fluid adenosine deaminase activity in the diagnosis of tuberculous meningitis in adults

We studied an adenosine deaminase (ADA) activity in the cerebrospinal fluid (CSF) of 182 patients with meningitis. The patients were subdivided into four groups, (1) 36 cases of tuberculous meningitis; (2) 130 cases of viral or aseptic meningitis; (3) nine cases of bacterial meningitis; (4) seven cases of cryptococcal meningitis. Mean+/-S.D. ADA activity was 12.76+/-7.53 U/l in group 1; 2.58+/-2.37 U/l in group 2; 7.38+/-3.27 U/l in group 3; 7.42+/-4.38 U/l in group 4. Comparing the ADA activity in each group with the other groups, the difference is significant (P<0.001), except between groups 3 and 4. The sensitivity of the test for group 1 compared with group 2 was 0.83 and the specificity was 0.95 when a cut-off value of 7 U/l was used. When group 1 was compared with groups 3 and 4, the sensitivity was 0.58 and the specificity was 0.89 and 0.71 with groups 3 and 4, respectively, when a cut-off value of 10 U/l was used. Values >15 U/l were not observed in any of the non-tuberculous meningitis patients; therefore, ADA activity >15 U/l could be a strong indication of tuberculous meningitis. We conclude that a determination of CSF ADA can aid in the early differential diagnosis of tuberculous meningitis.

Adenosine deaminase: functional implications and different classes of inhibitors

Adenosine deaminase (ADA) is an enzyme of the purine metabolism which catalyzes the irreversible deamination of adenosine and deoxyadenosine to inosine and deoxyinosine, respectively. This ubiquitous enzyme has been found in a wide variety of microorganisms, plants, and invertebrates. In addition, it is present in all mammalian cells that play a central role in the differentiation and maturation of the lymphoid system. However, despite a number of studies performed to date, the physiological role played by ADA in the different tissues is not clear. Inherited ADA deficiency causes severe combined immunodeficiency disease (ADA-SCID), in which both B-cell and T-cell development is impaired. ADA-SCID has been the first disorder to be treated by gene therapy, using polyethylene glycol-modified bovine ADA (PEG-ADA). Conversely, there are several diseases in which the level of ADA is above normal. A number of ADA inhibitors have been designed and synthesized, classified as ground-state and transition-state inhibitors. They may be used to mimic the genetic deficiency of the enzyme, in lymphoproliferative disorders or immunosuppressive therapy (i.e., in graft rejection), to potentiate the effect of antileukemic or antiviral nucleosides, and, together with adenosine kinase, to reduce breakdown of adenosine in inflammation, hypertension, and ischemic injury.

[Adenosine deaminase in the cerebrospinal fluid of patients with acquired immunodeficiency syndrome]

The adenosine-deaminase (ADA) activity was evaluated in CSF samples from 263 patients with AIDS. An elevated ADA activity in CSF was found in patients with: antibodies to toxoplasmosis, syphilis or cytomegalovirus; Cryptococcus neoformans or their antigens; tuberculous meningitis; lymphoma. There was no statistical difference among all these groups in respect to ADA activity. However, the ADA activity in CSF from AIDS patients without CSF changes other than HIV antibodies, even unspecific changes, was not elevated. This may suggest that ADA is related to AIDS associated pathologies activity rather than to HIV infection itself.

Adenosine deaminase concentration in cerebrospinal fluid during brucella meningitis

Adenosine deaminase (ADA) activity was measured in the CSF of five patients with confirmed brucella meningitis. The mean enzyme value was 20.00 U/l in the presence of high lymphocyte counts in the CSF. We conclude from this preliminary result that the quick and simple estimation of ADA in CSF could be of great value in the diagnosis of brucella meningitis as the enzyme concentration was high in all five patients. This finding is however not specific and similar results have been reported in other meningitides such as tuberculous meningitis.