L3T4(CD4)-, Lyt-2(CD8)- and Mac-1(CD11b)-phenotypic leukocytes in murine cryptococcal meningoencephalitis

Abstract

An immunohistological study of L3T4(CD4)+ and LYT-2(CD8)+ lymphocytes, Mac-1(CD11b)+ monocytes and granulocytes in experimental murine cryptococcal meningoencephalitis was conducted. To assess the concomitant inflammatory reaction in an extracerebral site, livers were examined in parallel. Mice were infected i.v. with Cryptococcus neoformans, group A/D, and organs were examined immunohistologically for CD4-, CD8- and monocyte- and granulocyte-specific CD11b-phenotypic leukocytes over a period of 60 days. Intracerebrally, agglomerations of cryptococci formed pseudocysts that were surrounded by CD4+ and CD8+ lymphocytes at the end of the second week post-infection, followed by the invasion of monocytes and granulocytes into the lesions. After the fourth week post-infection, most of the invaded lesions were transformed into glious scars. Meningitis was usually marked and showed a homogenous distribution of CD4-, CD8- and CD11b-phenotypic cells, with a predominance of monocytes and CD4+ lymphocytes. Inflammatory infiltrates in the liver were found already 4 days post-infection. CD4+ lymphocytes and monocytes were distributed homogeneously in the infiltrates, with a lower number of CD8+ lymphocytes being located rather in the periphery of the infiltrates. Comparing leukocyte kinetics in brain and liver, an important observation was the delayed immigration of immune cells at the intracerebral cryptococcal lesions as compared with the liver, and the different migration patterns of T-lymphocyte subgroups and macrophages. These results suggest that there are differential leukocyte migration patterns in the liver and brain following disseminated cryptococcosis. The immunological aspects of the observed leukocyte kinetics are discussed.

Cytokine and Inducible Nitric Oxide Synthase mRNA Expression during Experimental Murine Cryptococcal Meningoencephalitis

“…phages and neutrophils, and activated resident cells (e.g., microglia, astrocytes, and endothelial cells) (6,7,10,17,31,57).…”

“…Each DNase-treated RNA sample (5 g) was reverse transcribed using 1 l (0.5 g) of oligo(dT) [12][13][14][15][16][17][18] primer (GibcoBRL), 1 l (200 U) of SuperScript II reverse transcriptase (GibcoBRL), 1 l (40 U) of RNasin (Promega), 5 l of 5 mM (each) deoxynucleoside triphosphate (Sigma, St. Louis, Mo. ), 5 l of 0.1 M dithiothreitol (GibcoBRL), 10 l of 5ϫ enzyme buffer (GibcoBRL), and 22 l of DEPC-treated water (total reaction volume, 50 l).…”

“…The immunopathogenesis of central nervous system (CNS) infection remains incompletely understood (10,36). Previous studies have suggested that phagocytic effector cells in the brain (e.g., microglia and astrocytes), as well as cell-mediated immunity (CMI) and cytokine release, all play roles in brain-specific immune response (1,11,17,23,32,40).…”

Cellular Immune Activation in Cerebrospinal Fluid From Ugandans With Cryptococcal Meningitis and Immune Reconstitution Inflammatory Syndrome

“…Cryptococcus is proposed to cross the blood-brain barrier through 3 mechanisms: via endothelial cells when tight junctions are damaged or weakened (paracellular) [ 4 ], via brain endothelial cells (transcytosis) [ 5 ], or within infected monocytes or macrophages (Trojan horse) [ 6 ]. Aerosol infection of mice with Cryptococcus spores elicits a self-limited subclinical pneumonia, accompanied sequentially by local recognition of the fungus by alveolar macrophages and neutrophils, then by monocytes and finally expansion of Cryptococcus -specific CD4 + and CD8 + T cells [ 7 , 8 ], which parallels the immunopathogenesis in the cerebrospinal fluid (CSF) with meningitis [ 9 ]. Similarly, in healthy individuals, the initial immune response in the lung involves fungal recognition by innate immune cells and subsequent expansion of Cryptococcus -specific CD4 + T cells to control the infection [ 7 ].…”