Stimulation of the Protective Response to Actinomycetoma by <i>Nocardia brasiliensis</i> in Mice Treated with <i>Candida albicans</i> Antigens

Abstract

Actinomycetoma is a chronic subcutaneous lesion caused by the pathogenic bacterium Nocardia ( N .) brasiliensis . Yeast antigens of Candida ( C .) albicans increase the interferon (IFN)- γ and TCD4+ cells levels that enhance the phagocytic killing of N . brasiliensis , able to survive inside phagocytes and to grow in clustered colonies that form grains. The aim of this work was to test the effect of a crude protein extract of C . albicans on the levels of IFN- γ producing TCD4+ cells and on the outcome of actinomycetoma lesion. Five BALB/c mice with N . brasiliensis infection at left hind footpad were treated four times every other day with C. albicans crude protein extract (CPE). Five uninfected mice treated with CPE or infected mice treated with sterile phosphate-saline buffer were included as positive and negative control groups, respectively. Footpad thickness was recorded in all groups. Once the treatments were finished, single cell suspensions from blood and spleen were prepared for assessing the amount (%) of IFN- γ producing TCD4+ cells by cytofluorometry; presence of TCD4+ and IFN- γ in footpad sections was detected by immunofluorescence and immunohistochemistry, respectively. By comparison with the negative control group, infected mice treated with CPE had lower footpad thickness, higher percentage of blood and spleen IFN- γ producing TCD4+ cells as well as in situ presence of IFN- γ and TCD4+ cells. These findings showed that CPE from C . albicans displayed an immunoadjuvant activity that enhanced the presence of IFN- γ producing TCD4+ cells and IFN- γ for the resolution of N . brasiliensis actinomycetoma in mice.