ORIGINAL ARTICLE

Tissue invasiveness and non-acidic pH in human candidiasis correlate with "in vivo" expression by Candida albicans of the carbohydrate epitope recognised by new monoclonal antibody 1H4

C Monteagudo¹, A Viudes², A Lazzell², J P Martinez³ and J L Lopez-Ribot²

¹ Department of Pathology University of Valencia, 46010 – Valencia, Spain
² Department of Medicine, Division of Infectious Diseases, The University of Texas Health Science Center at San Antonio, Texas TX 78245, USA
³ Department of Microbiology, University of Valencia, 46010 – Valencia, Spain

Correspondence to:
Correspondence to:
Dr C Monteagudo
Departamento de Patología, Facultad de Medicina, Avda. Blasco Ibañez 17, 46010 - Valencia, Spain; Carlos.Monteagudo{at}uv.es

Background: The morphogenetic conversion between yeast and hyphal growth forms appears to be crucial in the pathogenesis of invasive candidiasis, and can be regulated by environmental signals such as extracellular pH.

Aims: To characterise the epitope recognised by monoclonal antibody 1H4, and to evaluate the expression of its corresponding epitope in Candida albicans cells under different conditions of pH and temperature, and "in vivo", in tissue samples from patients with human candidiasis.

Methods: Monoclonal antibody 1H4 was generated against the 58 kDa cell wall mannoprotein of C albicans (mp58), and was further characterised by immunoblot analysis, periodate treatment of the antigenic preparations, and agglutination experiments of C albicans strains 3153A, SC5314, and 412, cultured under different environmental conditions (growth media and pH). An immunohistochemical study was performed in 24 human tissue samples from patients with mucocutaneous and systemic candidiasis.

Results: 1H4 recognises a pH sensitive carbohydrate epitope on the surface of C albicans cells, and this epitope is not restricted to mp58, but is shared with other cell wall mannoproteins. Immunohistochemical findings indicated that expression of the 1H4 epitope on C albicans cells in tissue sections from human candidiasis correlates with tissue invasion and pH of the niche. 1H4 immunoreactivity was also found in candida remnants within macrophages.

Conclusions: The fact that 1H4 epitope expression selectively identifies invasive forms of C albicans, in addition to candida remnants within macrophages, supports its potential value in the diagnosis and management of human candidiasis.

Keywords: invasive candidiasis; monoclonal antibody; pH; Candida albicans; immunohistochemistry

Abbreviations: ßME, ß mercaptoethanol; BSA, bovine serum albumin; ELISA, enzyme linked immunosorbent assay; mp58, 58 kDa cell wall mannoprotein; SDS-PAGE, sodium dodecyl sulfate polyacrylamide gel electrophoresis; TBS, Tris buffered saline; YPD, yeast peptone dextrose

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