Techniques in human airway inflammation: Differences in plastic-embedded and snap-frozen sections for CD3, CD4, and CD8 immunostaining of bronchial biopsy specimens

Today, the quantification of inflammatory cells in human airway biopsies might be facilitated by better morphologic resolution provided by special resin (plastic)-embedding techniques. The present study compares the numbers of CD3-, CD4-, and CD8-positive cells in glycolmethacrylate-embedded versus snap-frozen biopsy specimens of normal bronchial mucosa in 10 patients with various pulmonary diseases. In general, larger numbers of CD3-, CD4-, and CD8-positive cells were counted in snap-frozen specimens than in plastic-embedded ones. Loss of antigenic properties during storage of plastic-embedded tissue (blocks) might have contributed to the weak correlation between both methods. An additional study showed that the number of CD3-, CD4-, and CD8-positive cells decreased significantly within a few months after embedding in glycolmethacrylate, Therefore, we recommend processing glycolmethacrylate-embedded specimens as soon as possible. For standard evaluation of established inflammatory cell parameters such as CD3, CD4, CD8, and EG2, frozen tissue is preferable because of the ease of the method and its reliable cell counting. Because glycolmethacrylate-embedded tissue shows superior morphologic resolution, under strict rules, this method seems attractive for the study, in particular, of cell-cell and cell-matrix relationships.