Monoclonal Antibody Staining Improves Detection of Gastric Bacteria

Tissue sections cut from paraffin blocks can be immunochemically stained with polyclonal or specific monoclonal antibodies and examined microscopically to determine the presence or absence of H. pylori.

A retrospective study, conducted by PLUS Diagnostics Laboratories, Union, NJ, USA), used archived material of 300 biopsies that previously had been demonstrated as H. pylori gastritis. The polyclonal antibody immunohistochemical method (NCL-HPp) were compared with slides stained with a Novocastra monoclonal antibody, clone UCL3R (MHP). A monoclonal slide and a polyclonal slide were each prepared with two sections from the same level, that were cut at four micrometer thickness, and immunohistochemical staining was performed on the Bond instrument (Leica Microsystems, Wetzlar, Germany), from whom both the monoclonal and polyclonal antibodies are available.

All study immunohistochemical stained tissue slides were reviewed microscopically by two gastrointestinal pathologists from PLUS Diagnostics with extensive experience in interpretation of immunohistochemical stains and H. pylori assessment. Each set of histological sections were scored, and the results recorded. Results were classified as either positive or negative for H. pylori. The definition of a positive result was the presence of any stained organisms resembling H. pylori bacteria. The definition of negative was the absence of any stained H. pylori-like bacteria.

The sensitivity of the two methods was comparable with 96.2% of the cases identified by the monoclonal antibody method and 98.5% identified by the polyclonal antibody method. The pathologists' evaluations showed that 75.6% of cases displayed high quality organism morphology with the MHP compared with only 34.4% using NCL-HPp, and that 95.8% of cases displayed high quality background staining MHP compared with 87.3% using NCL-HPp.

The authors concluded that the new H. pylori monoclonal ULC3R antibody reagent (MHP) when compared to the polyclonal antibody, NCL-HPp, shows improved quality of organism morphology clarity and reduced nonspecific background staining, whereas the sensitivity of the two methods was comparable. The study was published in January 2011, in LabMedicine.

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