Agglutination of Histoplasma capsulatum by IgG monoclonal antibodies against Hsp60 impacts macrophage effector functions.
Histoplasma capsulatum can efficiently survive within macrophages, facilitating H. capsulatum translocation from the lung into the lymphatics and bloodstream. We have recently generated monoclonal antibodies (MAbs) to an H. capsulatum surface-expressed heat shock protein of 60 kDa (Hsp60) that modify disease in a murine histoplasmosis model. Interestingly, the MAbs induced different degrees of yeast cell agglutination in vitro. In the present study, we characterized the agglutination effects of the antibodies to Hsp60 on H. capsulatum yeast cells by light microscopy, flow cytometry, dynamic light scattering, measuring zeta potential, and using optical tweezers. We found that immunoglobulin Gs (IgGs) to Hsp60 cause H. capsulatum aggregation dependent on the (i) concentration of MAbs, (ii) MAb binding constant, and (iii) IgG subclass. Furthermore, infection of macrophages using agglutinates of various sizes after incubation with different Hsp60-binding MAbs induced association to macrophages through distinct cellular receptors and differentially affected macrophage antifungal functions. Hence, the capacity of IgG MAbs to agglutinate H. capsulatum significantly impacted pathogenic mechanisms of H. capsulatum during macrophage infection, and the effect was dependent on the antibody subclass and antigen epitope.
Department of Medicine (Division of Infectious Diseases), Albert Einstein College of Medicine of Yeshiva University, Bronx, New York, USA.
Allan Jefferson
AJ
Guimarães
Susana
S
Frases
Bruno
B
Pontes
Mariana Duarte
MD
de Cerqueira
Marcio L
ML
Rodrigues
Nathan Bessa
NB
Viana
Leonardo
L
Nimrichter
Joshua Daniel
JD
Nosanchuk
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology*; D000915:Antibody Affinity; D039481:CD11b Antigen / Q000235:genetics / Q000378:metabolism; D018834:Chaperonin 60 / Q000276:immunology*; D005260:Female; D005786:Gene Expression Regulation / Q000276:immunology; D006658:Histoplasma / Q000276:immunology*; D007074:Immunoglobulin G / Q000276:immunology*; D008264:Macrophages / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout
D000911:Antibodies, Monoclonal; D039481:CD11b Antigen; D018834:Chaperonin 60; D007074:Immunoglobulin G