Evaluation of risk and diagnostic value of quantitative assays for anti-Toxoplasma gondii immunoglobulin A (IgA), IgE, and IgM and analytical study of specific IgG in immunodeficient patients

Abstract

To determine their prognostic and diagnostic values for toxoplasmosis in immunodepressed subjects, we assayed immunoglobulin A (IgA) and IgE antibodies by means of immunocapture (IC) tests, with revelation done by using a suspension of T. gondii (ICT). We also carried out a simultaneous analytical study of IgG antibodies on cellulose acetate membranes by using the comparative immunological profile method and an enzyme-linked immunofiltration assay (ELIFA). A total of 1,238 samples (serum, cerebrospinal fluid, and aqueous humor from 318 patients) were tested. IgA and IgE antibodies were detected in all heart, kidney, and liver transplant recipients with clinical manifestations of toxoplasmosis; IgA was detected in the aqueous humor of a patient with chorioretinitis. In patients with AIDS-related toxoplasmosis, including the cerebral form, IgA and IgE antibodies or a significant modification of ELIFA IgG values were observed in 38, 19, and 25% of patients, respectively. IgM was detected by ICT only in 12% of patients and aided the diagnosis in 1 of 71 patients. IC tests for specific IgA and IgE alone and combined with ELIFA were positive in 39 and 46% of patients who developed clinical toxoplasmosis, respectively. In a serial study of 16 patients in whom at least one of these three tests was positive, a significant immunological signal sometimes preceded clinical onset by 1, 6, and even 17 months. Similarly, in a group of human immunodeficiency virus-infected patients with evidence of previous exposure to T. gondii but no clinical manifestations, IgA, IgE, and IgA and/or IgE antibodies were detected in only 11, 4, and 12% of patients, respectively. These two situations point to peripheral T. gondii reactivation. IgA and IgE emerged as interesting markers of the risk of toxoplasmosis in immunodepressed patients. They may also provide valuable assistance in the diagnosis of toxoplasmosis, especially because tests for specific IgM are disappointing. However, at least one in two patients with toxoplasmosis showed no detectable immunological reaction, suggesting that this polyisotypic approach should be combined with other noninvasive methods such as gene amplification.

Recombinant Antigens To DetectToxoplasma gondii-Specific Immunoglobulin G and Immunoglobulin M in Human Sera by Enzyme Immunoassay

“…(iii) Detection of Toxoplasma-specific IgA. An immunocapture IgA assay (IC-A) was used for the detection of Toxoplasma-specific IgA as previously described (41).…”

Toxoplasma gondii Infection and Chronic Liver Diseases: Evidence of an Association

“…According to previous clinical and epidemiological studies, some reports highlighted a potential association between T. gondii infection and CLD [ 8 , 9 ]. However, these studies are based on serological tests that are inefficient and inadequate for detecting active infection in immunodepressed subjects [ 10 , 11 ]. The use of molecular diagnosis is particularly appropriate for such patients, since it does not depend on the immunological status of the host.…”

Detection of Specific Immunoglobulin E during Maternal, Fetal, and Congenital Toxoplasmosis

“…The aim of this study was to evaluate IgE Ab as a specific marker of recent or progressive T. gondii infection. Few studies on this isotype have been published (1,10,14,15,25). The method that we used to detect specific IgE was based on immunocapture with revelation by use of a suspension of tachyzoites.…”

“…To improve the dating of T. gondii infection and to unmask longstanding progressive toxoplasmosis, we tried to identify an early, briefly appearing marker of recent infection. To this end, we developed an assay for antitoxoplasmic IgE (14,25) and applied it to assessing the risk of toxoplasmosis in pregnant women and to the diagnosis of CT. We report our experience in these situations; reactivation in immunodeficient patients was the subject of a previous article (15).…”