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L3T4(CD4)-, Lyt-2(CD8)- and Mac-1(CD11b)-phenotypic leukocytes in murine cryptococcal meningoencephalitis
1Institut für Medizinische Mikrobiologie und Infektionsimmunologie, Berlin, Federal Republic of Germany.
Insights
Immune cell migration to the brain in cryptococcal meningoencephalitis is slower than in the liver, with distinct patterns for T-lymphocyte subsets and macrophages in mice.
Area of Science:
- Immunology
- Neuroscience
- Infectious Diseases
Background:
- Cryptococcal meningoencephalitis is a serious central nervous system infection.
- Understanding the host immune response, particularly leukocyte infiltration, is crucial for treatment.
- Murine models provide insights into the pathogenesis of cryptococcal infections.
Purpose of the Study:
- To investigate the immunohistological characteristics of leukocyte infiltration in experimental murine cryptococcal meningoencephalitis.
- To compare the kinetics and patterns of immune cell migration in the brain versus the liver.
- To elucidate differential immune responses in central nervous system versus extracerebral sites during disseminated cryptococcosis.
Main Methods:
- Mice were infected intravenously with Cryptococcus neoformans (group A/D).
- Immunohistology was used to examine brain and liver tissues over 60 days.
- Leukocyte populations, including CD4+ and CD8+ lymphocytes, monocytes (CD11b+), and granulocytes, were phenotypically identified.
Main Results:
- Intracerebral lesions showed agglomerations of Cryptococcus surrounded by CD4+ and CD8+ lymphocytes, followed by monocytes and granulocytes, eventually forming glial scars.
- Meningitis exhibited a homogeneous distribution of leukocytes, with a predominance of monocytes and CD4+ lymphocytes.
- Liver infiltrates appeared earlier (4 days post-infection) with homogeneous CD4+ lymphocytes and monocytes, and peripheral CD8+ lymphocytes; intracerebral immune cell immigration was delayed compared to the liver.
Conclusions:
- Differential leukocyte migration patterns occur in the brain and liver during disseminated cryptococcosis.
- The brain exhibits delayed immune cell immigration and distinct cellular composition compared to the liver.
- These findings highlight site-specific immune responses in 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.