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Differential phagocytosis of white versus opaque Candida albicans by Drosophila and mouse phagocytes.

Lohse MB, Johnson AD - PLoS ONE (2008)

Bottom Line: The human fungal pathogen Candida albicans resides asymptomatically in the gut of most healthy people but causes serious invasive diseases in immunocompromised patients.This difference is seen both in the overall percentage of cultured cells that phagocytose white versus opaque C. albicans and in the average number of C. albicans taken up by each phagocytic cell.We conclude that susceptibility to phagocytosis by cells of the innate immune system is an important distinction between white and opaque C. albicans, and propose that one role of switching from the prevalent white form into the rarer opaque form may be to allow C. albicans to escape phagocytosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California, USA.

ABSTRACT
The human fungal pathogen Candida albicans resides asymptomatically in the gut of most healthy people but causes serious invasive diseases in immunocompromised patients. Many C. albicans strains have the ability to stochastically switch between distinct white and opaque cell types, but it is not known with certainty what role this switching plays in the physiology of the organism. Here, we report a previously undescribed difference between white and opaque cells, namely their interaction with host phagocytic cells. We show that both Drosophila hemocyte-derived S2 cells and mouse macrophage-derived RAW264.7 cells preferentially phagocytose white cells over opaque cells. This difference is seen both in the overall percentage of cultured cells that phagocytose white versus opaque C. albicans and in the average number of C. albicans taken up by each phagocytic cell. We conclude that susceptibility to phagocytosis by cells of the innate immune system is an important distinction between white and opaque C. albicans, and propose that one role of switching from the prevalent white form into the rarer opaque form may be to allow C. albicans to escape phagocytosis.

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D. melanogaster S2 cells more efficiently phagocytose white than opaque C. albicans.(A) D. melanogaster S2 cells were co-incubated with white or opaque C. albicans for 1, 2, or 3.5 hours, fixed, and stained as described in the Materials and Methods. The number of S2 cells phagocytosing one or more C. albicans cells was determined. (B) For the same sets of S2 cells, the number of C. albicans cells phagocytosed by S2 cells was quantified and the total number of C. albicans cells phagocytosed divided by the number of S2 cells scored, referred to as the phagocytic index, was plotted. Values plotted are the averages from four data sets from a given day and error bars represent the standard deviation. 100 S2 cells were counted for each data set. For the 3.5 hour time point, statistical significance of differences from the white a/a strain was evaluated using a t-test assuming unequal variance, sets with p<.001 are marked with an asterisk.
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pone-0001473-g002: D. melanogaster S2 cells more efficiently phagocytose white than opaque C. albicans.(A) D. melanogaster S2 cells were co-incubated with white or opaque C. albicans for 1, 2, or 3.5 hours, fixed, and stained as described in the Materials and Methods. The number of S2 cells phagocytosing one or more C. albicans cells was determined. (B) For the same sets of S2 cells, the number of C. albicans cells phagocytosed by S2 cells was quantified and the total number of C. albicans cells phagocytosed divided by the number of S2 cells scored, referred to as the phagocytic index, was plotted. Values plotted are the averages from four data sets from a given day and error bars represent the standard deviation. 100 S2 cells were counted for each data set. For the 3.5 hour time point, statistical significance of differences from the white a/a strain was evaluated using a t-test assuming unequal variance, sets with p<.001 are marked with an asterisk.

Mentions: Using this assay, we compared the ability of S2 cells to phagocytose white and opaque C. albicans cells of exactly the same genotype. S2 cells were co-incubated with either white or opaque C. albicans at a multiplicity of infection (MOI) of 5. After various time periods, the samples were fixed and stained as described in Materials and Methods. From each infection, four separate sets of 100 S2 cells were scored for phagocytosis of C. albicans cells and the values averaged. After a 2 hour co-incubation, approximately 5-fold more S2 cells had taken up at least one white cell than had taken up at least one opaque cell, even though the S2 cells were exposed to equal numbers of C. albicans cells (FIG. 2A). Similar differences were also seen after 3.5 hours of co-incubation. This difference was independent of mating type: a/a whites were phagocytosed similarly to a/α (FIG. 2B) and α/α whites, while a/a opaques were phagocytosed similarly to α/α opaques (data not shown). This difference between whites and opaques repeated on multiple days and in multiple C. albicans strain backgrounds despite fluctuations in overall levels of phagocyosis. Previous studies have shown that S2 cells preferentially phagocytose C. albicans white cells over non-pathogenic S. cerevisiae [15]; the level of opaque cell phagocytosis we observed in this study is approximately equal to that of S. cerevisisae (data not shown).


Differential phagocytosis of white versus opaque Candida albicans by Drosophila and mouse phagocytes.

Lohse MB, Johnson AD - PLoS ONE (2008)

D. melanogaster S2 cells more efficiently phagocytose white than opaque C. albicans.(A) D. melanogaster S2 cells were co-incubated with white or opaque C. albicans for 1, 2, or 3.5 hours, fixed, and stained as described in the Materials and Methods. The number of S2 cells phagocytosing one or more C. albicans cells was determined. (B) For the same sets of S2 cells, the number of C. albicans cells phagocytosed by S2 cells was quantified and the total number of C. albicans cells phagocytosed divided by the number of S2 cells scored, referred to as the phagocytic index, was plotted. Values plotted are the averages from four data sets from a given day and error bars represent the standard deviation. 100 S2 cells were counted for each data set. For the 3.5 hour time point, statistical significance of differences from the white a/a strain was evaluated using a t-test assuming unequal variance, sets with p<.001 are marked with an asterisk.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2198939&req=5

pone-0001473-g002: D. melanogaster S2 cells more efficiently phagocytose white than opaque C. albicans.(A) D. melanogaster S2 cells were co-incubated with white or opaque C. albicans for 1, 2, or 3.5 hours, fixed, and stained as described in the Materials and Methods. The number of S2 cells phagocytosing one or more C. albicans cells was determined. (B) For the same sets of S2 cells, the number of C. albicans cells phagocytosed by S2 cells was quantified and the total number of C. albicans cells phagocytosed divided by the number of S2 cells scored, referred to as the phagocytic index, was plotted. Values plotted are the averages from four data sets from a given day and error bars represent the standard deviation. 100 S2 cells were counted for each data set. For the 3.5 hour time point, statistical significance of differences from the white a/a strain was evaluated using a t-test assuming unequal variance, sets with p<.001 are marked with an asterisk.
Mentions: Using this assay, we compared the ability of S2 cells to phagocytose white and opaque C. albicans cells of exactly the same genotype. S2 cells were co-incubated with either white or opaque C. albicans at a multiplicity of infection (MOI) of 5. After various time periods, the samples were fixed and stained as described in Materials and Methods. From each infection, four separate sets of 100 S2 cells were scored for phagocytosis of C. albicans cells and the values averaged. After a 2 hour co-incubation, approximately 5-fold more S2 cells had taken up at least one white cell than had taken up at least one opaque cell, even though the S2 cells were exposed to equal numbers of C. albicans cells (FIG. 2A). Similar differences were also seen after 3.5 hours of co-incubation. This difference was independent of mating type: a/a whites were phagocytosed similarly to a/α (FIG. 2B) and α/α whites, while a/a opaques were phagocytosed similarly to α/α opaques (data not shown). This difference between whites and opaques repeated on multiple days and in multiple C. albicans strain backgrounds despite fluctuations in overall levels of phagocyosis. Previous studies have shown that S2 cells preferentially phagocytose C. albicans white cells over non-pathogenic S. cerevisiae [15]; the level of opaque cell phagocytosis we observed in this study is approximately equal to that of S. cerevisisae (data not shown).

Bottom Line: The human fungal pathogen Candida albicans resides asymptomatically in the gut of most healthy people but causes serious invasive diseases in immunocompromised patients.This difference is seen both in the overall percentage of cultured cells that phagocytose white versus opaque C. albicans and in the average number of C. albicans taken up by each phagocytic cell.We conclude that susceptibility to phagocytosis by cells of the innate immune system is an important distinction between white and opaque C. albicans, and propose that one role of switching from the prevalent white form into the rarer opaque form may be to allow C. albicans to escape phagocytosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California, USA.

ABSTRACT
The human fungal pathogen Candida albicans resides asymptomatically in the gut of most healthy people but causes serious invasive diseases in immunocompromised patients. Many C. albicans strains have the ability to stochastically switch between distinct white and opaque cell types, but it is not known with certainty what role this switching plays in the physiology of the organism. Here, we report a previously undescribed difference between white and opaque cells, namely their interaction with host phagocytic cells. We show that both Drosophila hemocyte-derived S2 cells and mouse macrophage-derived RAW264.7 cells preferentially phagocytose white cells over opaque cells. This difference is seen both in the overall percentage of cultured cells that phagocytose white versus opaque C. albicans and in the average number of C. albicans taken up by each phagocytic cell. We conclude that susceptibility to phagocytosis by cells of the innate immune system is an important distinction between white and opaque C. albicans, and propose that one role of switching from the prevalent white form into the rarer opaque form may be to allow C. albicans to escape phagocytosis.

Show MeSH
Related in: MedlinePlus