Comparative Immunopathology of Toxoplasma gondii Natural Infections in Marmosets (Callithrix spp.) and Howler Monkeys (Alouatta spp.), Brazil.

INTRODUCTION

Neotropical primates (NTPs) present varying susceptibility to toxoplasmosis caused by Toxoplasma gondii, but their immunopathogenic responses remain poorly understood.

MATERIALS AND

METHODS

Local immune responses were characterized in the liver, spleen, and central nervous system (CNS) of 50 naturally infected NTPs (31 Callithrix spp.; 19 Alouatta spp.) by immunohistochemistry. Splenic white pulp morphometry, CD3+ T lymphocyte, Iba1+ macrophage/microglia, polymorphonuclear neutrophil quantification, and IFN-γ and IL-10 semi-quantification were performed.

RESULTS

Both genera exhibited splenic white pulp hyperplasia. Within genera, marmosets showed predominant CD3+ infiltrates in the spleen and histiocytic infiltrates in the liver and CNS, whereas howler monkeys exhibited predominantly histiocytic infiltrates in all tissues. Between genera, marmosets had significantly higher splenic CD3+ T-cell (p < 0.05), Iba1+ macrophage (p = 0.030), and IFN-γ (p = 0.018) immunolabeling than howler monkeys.