CD 15

Accurate (C3D-1), Becton Dickinson (Leu M1), Biodesign (B428, 80H5, G15), Biogenex (Tu9), Cymbus Bioscience (28), Dako (C3D-1), Immunotech (80H5), Novocastra, Research Diagnostics (28), Sanbio (BL-G15), Seralab (MC-1) and Serotec (NH6, B-H8).

Fresh-frozen tissue and formalin-fixed, paraffin-embedded tissue. Muramidase pretreatment increases reactivity, particularly in acute myeloid leukemia.

A variety of antibodies to CD 15 have been generated in different ways but appear to have similar immunoreactivity patterns. Some antibodies were developed by immunization and screening against human hematopoietic cell lines and were originally felt to be specific for myeloid leukemias, while other antibodies were developed from specific human and mouse carcinoma cell lines and were later found to react with granulocytes and a variety of human carcinomas. The antibodies are mostly of IgM isotype and have the common property of being able to recognize a specific sugar sequence that occurs in the glycolipid lacto-N-fucopentaose III ceramide and is also found in several glycolipids such as glycoproteins. The sugar sequence is referred to as X hapten or Le and its highly immunogenic nature in mice has led to the production of several IgM monoclonal antibodies to the CD 15 cluster. The lacto-N-fucopentaose III has been identified in human milk and is virtually absent in benign human epithelium. A related substance lacto-N-fucopentaose II, is present in many benign human epithelial cells. The glycolipid, lacto-N-fucopentaose III has a structure similar to the Lewis blood group antigens. The CD 15 antigen exists in sialylated or unsialylated form, the former requiring prior digestion with muramidase to enable detection. Mature granulocytes and monocytes express the unsialylated molecule (Arber & Weiss, 1993).

CD 15 antibodies react with mature neutrophils; generally the reactivity is less with the less mature forms of the granulocyte series. Normal bone marrow myeloblasts are negative and some promyelocytes may not stain. Paraffin-embedded cells show both membrane and cytoplasmic staining. Normal platelets, red blood cells and B lymphocytes are routinely negative as are the vast majority of T lymphocytes. Mitogen-activated lymphocytes show positivity with the Leu M1 antibody and these are mostly T lymphocytes of the T4 subset. While some T8+ cells also express the antigen, a longer period of stimulation was needed to induce this finding.
In leukemia, CD 15 antibodies react with all neoplastic myeloid and monocytic proliferations although there is a variable pattern with different antibodies. CD 15 positivity is reported to be lost in cases of relapsed acute myeloid leukemia, correlating with a poorer survival. Almost all cases of chronic myelogenous leukemia have demonstrated the presence of CD 15 while in chronic phase. Approximately 16% of cases of acute lymphoblastic leukemia demonstrate the coexpression of at least one myeloid antigen and up to 50% of such cases are reportedly CD 15+ although the range of positivity is between 2% and 6%. CD 15 expression is highest in common acute lymphoblastic leukemia antigen (CALLA)-negative cases which generally have a worse prognosis than cases of CALLA-positive ALL (Bernstein et al, 1982).
CD 15 expression is very helpful in the diagnosis of Hodgkin's disease as almost all the CD 15 antibodies available react with Reed-Sternberg cells and the mononuclear variants. Characteristically, the staining is membranous with globular, juxtanuclear staining of the Golgi complex. The cytoplasmic membrane staining has been confirmed by ultrastructural studies and lysosomal granules contiguous with perinuclear vesicles representing the Golgi apparatus are also stained. Reed-Sternberg cells and atypical mononuclear variants in Hodgkin's disease of mixed cellularity type, nodular sclerosing and lymphocyte-depleted type show staining with CD15 antibodies. However, lymphocyte-predominant Hodgkin's disease is CD 15- particularly in the nodular and in some cases of the diffuse subtype (Stein et al, 1986). Digestion with neuraminidase has been reported to result in staining of the L&H cells in lymphocyte-predominant Hodgkin's disease although the staining has been described to be less intense and predominantly cytoplasmic in distribution. Similarly, enzyme pretreatment has been reported to produce positivity in T-cell lymphomas mostly of the mature phenotype, particularly in advanced stage mycosis fungoides. A smaller percentage of low-grade B-cell lymphomas have also been reported to be CD 15+.
CD 15 is a useful marker for granulocytic sarcoma, staining the majority of cases (Swerdlow & Wright, 1986). Strong CD 15 positivity has been found in carcinomas from a wide variety of sites. It is employed in a panel for the discrimination of adenocarcinoma from malignant mesothelioma, the latter being generally CD 15-. Cytomegalovirus infected cells have also been found to react with CD 15 antibodies, predominantly with cytoplasmic staining.

CD 15 antibodies are particularly useful for the identification of Reed-Sternberg cells, especially when they are employed in a panel which includes CD 45 (LCA), Reed-Sternberg cells showing the characteristic membranous and Golgi staining for CD 15 and negative staining for CD 45. It is also a useful discriminant when used in an appropriate panel for the separation of adenocarcinoma from malignant mesothelioma; adenocarcinomas and the antibodies label the myeloid cells of granulocytic sarcoma (Sewell et al, 1987). Staining is enhanced with microwave epitope retrieval using citrate buffer and enzyme digestion should not be performed when employed for the identification of Reed-Sternberg cells and adenocarcinomas.

•Aber DA, Weiss LM 1993. CD15:A review. Applied Immunohistochemistry 1: 17-30.

•Bernstein ID, Andrews RG, Cohen SF, McMaster BE 1982. Normal and malignant human myelocytic and monocytic cells identified by monoclonal antibodies. Journal of Immunology 128: 876-881.

•Sewell HF, Jaffray B, Thompson WD 1987. Reaction of monoclonal anti-Leu M1 - a myelomonocytic marker (CD15) - with normal and neoplastic epithelia. Journal of Pathology 151: 279-284.

•Stein H, Hansmann ML, Lennert K et al 1986. Reed-Sternberg and Hodgkin's cells in lymphocyte-predominant Hodgkin's disease of nodular subtype containing J chain. American Journal of Clinical Pathology 86: 292-297.

•Swerdlow SH, Wright SA 1986. A spectrum of Leu M1 staining in lymphoid and hemopoietic proliferations. American Journal of Clinical Pathology 85: 283-288.

Manual of diagnostic antibodies for immunohistology / Anthony S.-Y. Leong, Kumarasen Cooper, F. Joel W.-M. Leong.