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

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.