CD10 is a protein found on the surface of various cells throughout the body. It functions as a metalloendopeptidase, an enzyme that breaks down small peptides. This protein is also known as Common Acute Lymphocytic Leukemia Antigen (CALLA) or Neprilysin (NEP). CD10 is recognized for its presence in both normal biological processes and specific disease conditions.
Understanding CD10’s Normal Role
CD10, or Neprilysin (NEP), is a zinc-dependent metalloendopeptidase that plays a part in various physiological processes. It acts as an ectoenzyme, facilitating the breakdown of a variety of substrates. These substrates include peptide hormones like enkephalins, substance P, and atrial natriuretic peptide, thereby influencing pain signaling and cardiovascular regulation.
Beyond hormone regulation, CD10 contributes to cell growth, differentiation, and immune responses. Its enzymatic function helps regulate the activation of immune cells by degrading inflammatory peptides such as endothelin and bradykinin. It also plays a role in fetal development and cell proliferation.
In healthy tissues, CD10 shows specific expression patterns. It is found on the brush border of kidney tubules and intestinal epithelial cells, and in liver bile canaliculi. In lymphoid tissues, CD10 is present on early B-cell precursors, immature B cells, and germinal center B cells, as well as on mature neutrophils and some T-cell subsets.
CD10 is also expressed in non-hematopoietic cells and tissues, such as myoepithelial cells in the breast, fibroblasts, and epithelial cells in organs like the prostate and lungs.
CD10 in Blood Cancers
CD10 is an important marker in the diagnosis and classification of various blood cancers. Its strong association with Acute Lymphoblastic Leukemia (ALL), particularly B-cell ALL, is well-established. In B-lineage ALL, CD10 expression on blast cells is a key diagnostic feature and can correlate with certain favorable clinical characteristics, such as age and lower leukocyte counts.
The presence or absence of CD10 helps in distinguishing different subtypes of ALL. While CD10 is detected in approximately 94% of B-lineage ALL cases, its absence in this subgroup can be associated with specific genetic abnormalities, such as 11q23 chromosomal aberrations, which may indicate a distinct, higher-risk subset. For T-cell ALL, CD10 expression is less frequent, appearing in about 40% of cases, and its absence can be linked to a less favorable prognosis.
CD10 also aids in the classification of Non-Hodgkin Lymphomas, particularly Follicular Lymphoma (FL) and Diffuse Large B-cell Lymphoma (DLBCL). Most cases of Follicular Lymphoma (around 89%) express CD10, as it is a characteristic marker of germinal center B cells from which these lymphomas originate. The intensity of CD10 expression can help differentiate neoplastic B-cell processes from reactive follicular hyperplasia.
In Diffuse Large B-cell Lymphoma (DLBCL), CD10 expression is observed in a subset of cases, typically around 20% to 34%. Its presence in DLBCL is often associated with a germinal center B-cell origin, which can have implications for prognosis and treatment strategies. However, studies on its direct impact on survival in DLBCL have shown varied results, with some suggesting a correlation with shorter overall survival, while others find no significant influence.
CD10 expression in these blood cancers is commonly detected using techniques such as flow cytometry and immunohistochemistry. Flow cytometry analyzes cell surface markers on fresh tissue samples, while immunohistochemistry uses specific antibodies to visualize CD10 on fixed, paraffin-embedded tissue sections.
CD10 in Solid Tumors and Other Diseases
CD10’s expression extends beyond blood cancers, playing varied roles in solid tumors and other conditions. In Gastrointestinal Stromal Tumors (GIST), CD10 can be expressed, particularly in spindle cell GISTs originating from the small intestine, with about 19-24% of cases showing positivity. While not consistently present in all GISTs, its expression can be a useful diagnostic indicator in certain morphological subtypes and locations.
In breast cancer, CD10 is typically found in normal myoepithelial cells lining the ducts and lobules. Its consistent presence in these cells makes it a helpful marker for distinguishing invasive breast carcinoma, where myoepithelial cells are absent, from ductal carcinoma in situ. CD10 can also be expressed by stromal cells within breast tumors, and increased stromal CD10 expression has been linked to more aggressive tumor behavior and lymph node metastasis in some studies.
Clear cell renal cell carcinoma frequently expresses CD10, with approximately 75% to 100% of cases showing positivity. This makes CD10 a valuable marker for differentiating clear cell renal cell carcinoma from other kidney tumors, such as chromophobe renal cell carcinoma, which is generally negative for CD10. Its expression helps in confirming a renal origin for metastatic carcinomas.
CD10 is also a consistent marker for normal and neoplastic endometrial stromal cells. It shows diffuse immunoreactivity in endometrial stromal tumors, including endometrial stromal sarcoma, making it a reliable tool to distinguish these tumors from uterine smooth muscle tumors like leiomyomas and leiomyosarcomas, which are typically CD10-negative or show only focal positivity. CD10 immunoreactivity is also maintained in ectopic endometrial stromal cells, aiding in the diagnosis of endometriosis.