Conflict of interest

was not cross-reactive to Naegleria fowleri (brain-eating amoeba) seen in the autopsied brain of another patient. Regarding acanthamebic keratitis, see Figure 33. Of note is an exception that Balamuthia antigens were detectable by the diluted patient's serum only after heating pretreatment of deparaffinized sections in 10 mM citrate buffer, pH 6. Without heat-induced antigen retrieval, signals were not observed at all. Therefore, the author strongly recommends employing the heating pretreatment for immunostaining using patients'sera in order to avoid unexpected false negativity. Silane-coated glass slides should thus be used for preventing section

that heat-induced antigen retrieval is needed for visualizing B. mandrillaris antigens.

Immunohistochemistry - The Ageless Biotechnology

Balamuthia meningoencephalitis (left, H&E; center, reactivity with patient's own serum; right, reactivity with the serum of patient of acanthamebic meningoencephalitis). A healthy Japanese farmer housewife complained of progressive consciousness disturbance and seizure. At autopsy, hemorrhagic meningoencephalitis was observed. Large-sized, basophilic amebic trophozoites are microscopically clustered in Virchow-Robin's spaces. PCR analysis has disclosed infection of B. mandrillaris. Immunostaining using both the patient's own serum and the patient's serum of the abovementioned acanthamebic meningoencephalitis gives distinct positivity. Of note is

Undoubtedly, the detection of causative pathogens in the inflammatory lesion is the key step directing to the correct histopathological diagnosis of infectious diseases. Even if the specificity of the serum is unknown, the final diagnosis can be reached, based on the morphology and distribution of the positive signals, when combined with tissue reactions, laboratory data and clinical features. In the present article, the author introduced two different approaches using low-specificity antisera. The targets were formalin-fixed and paraffin-embedded sections. One approach is the use of commercially available rabbit antisera showing wide crossreactivity to a variety of bacteria, and another is the use of diluted patients'sera. Immunostaining using plural antimicrobial antisera commonly yielded clear positivity with low background, because of poor cross-reactivity of bacterial antigens to human cells and tissues. The approach described here was aimed at visualizing the causative bacteria within infectious lesions in routinely prepared paraffin sections through a wide cross-reactivity shown by low-specificity rabbit antisera

Immunostaining using patients'sera is also quite useful in making the histopathological diagnosis. Occasionally, IgG in the patients'sera showed crossreactivity to related pathogens wider than expected. In bacterial and fungal infection, the sera served as pan-bacterial and pan-fungal probes, respectively. Despite such broad/low specificity, this convenient procedure is excellent in selectively identifying the pathogen within the lesion in question. In viral, protozoal, and

detachment.

Figure 50.

6. Concluding remarks

against four kinds of bacteria.

108

The author has no conflict of interest in the present study.
