# Study on the T-Cell Immune Response in Individuals With HIV and Toxoplasmosis Using ELISPOT

## TL;DR

This study examines T-cell responses in HIV patients with toxoplasmosis using ELISPOT to detect immune activity against Toxoplasma gondii.

## Contribution

A modified 5-day ELISPOT protocol was developed to detect T-cell responses in immunocompromised HIV patients with toxoplasmosis.

## Key findings

- 27.6% of HIV-positive patients tested positive for Toxoplasma antibodies.
- HIV patients with toxoplasmosis had significantly lower CD4+ T cell counts.
- A modified ELISPOT method detected IFN-γ-producing T cells in all toxoplasmosis-positive HIV patients.

## Abstract

Introduction: The intracellular parasite Toxoplasma gondii stimulates the human immune system, resulting in the activation of both cellular and humoral immune responses. In HIV-infected individuals, latent Toxoplasma infection can reactivate, resulting in toxoplasmosis encephalitis (TE). Detection of specific memory T cells in such patients will prevent the risk of toxoplasmosis-related complications. ELISPOT assesses CD4+ and CD8+ T cell responses to antigens, and facilitates the identification of T. gondii-specific IFN-γ producing memory T cells in patients with both toxoplasmosis and HIV.

Patients and Methods: ELISA was used to test 104 blood samples from HIV + individuals for Toxoplasma antibodies. Peripheral blood mononuclear cells were isolated from the blood samples of the toxoplasmosis-positive HIV-infected patients and used to analyze the T-cell immune response. Peptides from the T. gondii were selected to stimulate CD4+ and CD8+ T cells when performing the ELISPOT.

Results: Serological data for toxoplasmosis was identified in 29 (27.6%) of the total number of patients. A significant difference was observed in the CD4+ T cell count between HIV-positive patients with and without toxoplasmosis. Seven of the HIV-infected patients with toxoplasmosis had a low CD4+/CD8+ T cell ratio. After performing a 16–20 h ELISPOT with peptide stimulation to investigate the presence of specific IFN-γ-producing cells in these seven patients, no IFN-γ-secreting cells were detected. Subsequently, a modified method was used, in which the immune cells were stimulated for a period of 5 days. At the end of this stimulation, all samples from HIV-infected patients with toxoplasmosis were ELISPOT positive, with a mean of 32 and 45 spots per well, respectively.

Conclusion: It is important to monitor patients with HIV, toxoplasmosis, and immunodeficiency. This can help prevent complications such as TE. A modified ELISPOT protocol may be required to determine the specific cell-mediated response in immunocompromised patients.