Background CD99 is a cell surface transmembrane glycoprotein expressed in various tissues. CD99 is differentially expressed between subpopulations of each tissue and is highly expressed in certain hematopoietic and precursor cells. However, there has been no comprehensive study of CD99 expression in normal skin. We evaluated CD99 expression in normal human skin and developing fetal skin.
Methods Seventy-five adult skin samples containing normal skin and eight fetal skin samples of different gestational ages were collected. CD99 immunohistochemical staining was performed to evaluate expression pattern in adult and fetal skin samples. CD99 and CD34 expression were compared by double immunofluorescence.
Results In normal adult skin, CD99 was strongly expressed in the membrane of epidermal basal keratinocytes, hair follicle bulges and outer root sheaths, and inner secretory cells of eccrine sweat glands. In fetal skin, CD99 was not expressed on the periderm at 16 weeks of gestation but was expressed in basal cells of fetal skin at around 19 weeks of gestation. CD99 expression became comparable to that of the adult skin after 20 weeks of gestation. CD99 and CD34 were co-expressed in hair follicle outer root sheaths, as seen by double immunofluorescence study.
Conclusions This is the first study examining CD99 expression pattern in normal adult and fetal skin. CD99 tends to be expressed in the basal/precursor cells of epidermis and in hair follicles. These results provide a basis for future investigation on functions of CD99 in the skin and provide a novel potential target for the treatment of dermatologic lesions.
Citations
Citations to this article as recorded by
Childhood pilomatrixoma mimicking malignant small round blue cell tumor with positivity for CD99: Potential pitfall in cytology Brijdeep Singh, Radhika Srinivasan, Deepak Bansal, Manish Rohilla, Pranab Dey, Uma Nahar Saikia, Ritambhra Nada Diagnostic Cytopathology.2023;[Epub] CrossRef
Role of CD99 in regulating homeostasis and differentiation in normal human epidermal keratinocytes Yi Li Wong, Toru Okubo, Eiko Uno, Kazuma Suda, Tsuyoshi Ishii Biochemical and Biophysical Research Communications.2022; 606: 108. CrossRef
“Neuroectodermal influence of CD 99 immunoexpression correlates with the clinical behavior of odontogenic cysts and tumors” Harshi Mishra, Nikita Gulati, Anshi Jain, Saurabh Juneja, Devi Charan Shetty Journal of Oral and Maxillofacial Pathology.2021; 25(3): 423. CrossRef
CD99 at the crossroads of physiology and pathology Michela Pasello, Maria Cristina Manara, Katia Scotlandi Journal of Cell Communication and Signaling.2018; 12(1): 55. CrossRef
CD99: A Cell Surface Protein with an Oncojanus Role in Tumors Maria Manara, Michela Pasello, Katia Scotlandi Genes.2018; 9(3): 159. CrossRef