The relative importance of CD4 and CD8T cells in immunity to pulmonary paracoccidioidomycosis

• Published in: Microbes and infection Vol. 9; no. 9; pp. 1078 - 1088
• Main Authors: Chiarella, Andressa P, Arruda, Celina, Pina, Adriana, Costa, Tania A, Ferreira, Rita C V, Calich, Vera L G
• Format: Journal Article
• Language: English
• Published: 01-07-2007
• ISSN: 1286-4579
• DOI: 10.1016/j.micinf.2007.04.016

Protective immunity in paracoccidioidomycosis (PCM) is believed to be mediated by cellular immunity, but the role of T cell subsets has never been investigated. The aim of this study was to characterize the function of CD4+ and CD8+ T cells in the immunity developed by susceptible, intermediate and resistant mice after P. brasiliensis infection. In susceptible mice, depletion of CD4+ T cells did not alter disease severity and anergy of cellular immunity but diminished antibody production. Anti-CD8 treatment led to increased fungal loads, but restored DTH reactivity. In resistant mice, both CD4+ and CD8+ T cells control fungal burdens and cytokines although only the former regulate DTH reactions and antibody production. In the intermediate strain, deficiency of whole T and CD8+ T cells but not of CD4+ T or B cells led to increased mortality rates. Thus, in pulmonary PCM: (a) irrespective of the host susceptibility pattern, fungal loads are mainly controlled by CD8+ T cells, whereas antibody production and DTH reactions are regulated by CD4+ T cells; (c) CD4+ T cells play a protective role in the resistant and intermediate mouse strains, whereas in susceptible mice they are deleted or anergic; (d) genetic resistance to PCM is associated with concomitant CD4+ and CD8+ T cell immunity secreting type 1 and type 2 cytokines.