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Published on: May 23, 2014
Phenotypic analysis and proliferative responses of human endometrial granulated lymphocytes during the menstrual
R F Searle1, R K Jones, J N Bulmer
1Departments of Immunology, University of Newcastle upon Tyne, The Medical School, United Kingdom.r.f.searle@newcastle.ac.uk
Insights
The function of endometrial granulated lymphocytes (eGLs) in the human uterus remains unclear. This study reveals that eGLs
Area of Science:
- Immunology
- Reproductive Biology
- Cell Biology
Background:
- The role of CD56+ CD16- endometrial granulated lymphocytes (eGLs) in human endometrium is not well understood.
- Increased eGL numbers in the secretory phase suggest a potential role in nonpregnant uterine immunobiology.
Purpose of the Study:
- To compare the phenotype and proliferative responses of eGLs during different menstrual cycle phases and early pregnancy.
- To investigate the in vivo function of eGLs in the human endometrium.
Main Methods:
- High purification of endometrial GLs (>98% CD56+) using immunomagnetic separation.
- Examination of cell surface antigen expression via double immunohistochemical labeling.
- Assessment of proliferative responses to mitogens and interleukin-2 (IL-2) using hanging drop cultures.
Main Results:
- eGLs showed increased expression of CD2, CD49a, and CD122 (IL-2 receptor beta) from the proliferative to the late secretory phase.
- CD49d expression was high and constant during the menstrual cycle but reduced in early pregnancy.
- eGLs from nonpregnant and pregnant endometrium proliferated in response to IL-2, with enhanced responses in the secretory phase and early pregnancy; PHA-induced proliferation was absent.
Conclusions:
- Endometrial eGLs exhibit differential expression of specific surface markers (CD2, CD49a, CD122) throughout the menstrual cycle.
- eGLs display distinct IL-2-induced proliferative capacities that vary with the menstrual cycle phase and pregnancy status.
- Differences in CD49d expression and PHA responsiveness distinguish eGLs between nonpregnant and pregnant endometrium.
Abstract:
The in vivo function of the unusual population of CD56+ CD16- endometrial granulated lymphocytes (eGLs) in human endometrium is unknown; their increased numbers in the secretory phase of the menstrual cycle suggests that they may play a role in the immunobiology of nonpregnant endometrium. In the present study, the phenotype and proliferative responses of eGLs at various phases of the menstrual cycle were compared with those in early pregnancy. Endometrial GLs were highly purified (> 98% CD56+) using immunomagnetic separation, and the expression of cell surface antigens was examined in smears using a double immunohistochemical labeling technique. Proliferative responses to mitogens and interleukin 2 (IL-2) were assessed in hanging drops in 60-well Terasaki plates. There was low to no expression of CD3, CD8, CD16, HML-1, L-selectin, and CD25 (IL-2 receptor alpha) on CD56+ cells isolated from nonpregnant and pregnant endometrium. The expression of CD2, CD49a, and CD122 (IL-2 receptor beta, IL-2Rbeta), however, increased from the proliferative to the late secretory phase of the menstrual cycle. In contrast, CD11a, CD69, and CD49d expression was high and did not vary with menstrual cycle phase; CD49d levels were significantly reduced in early pregnancy. Unlike early-pregnancy eGLs, none of the CD56+ eGL cultures throughout the menstrual cycle displayed phytohaemagglutinin (PHA)-induced lymphoproliferation. In contrast, eGLs from nonpregnant endometrium in the presence of 5 or 100 U/ml IL-2 after 48- and 120-h incubation showed significant proliferative responses, as did eGL cultures from early pregnancy. A significantly reduced number of proliferative phase eGL cultures proliferated in response to IL-2 compared to secretory phase and early-pregnancy eGL cultures. The IL-2-induced proliferative responses of CD56+ eGLs were associated with increased IL-2Rbeta (CD122) expression. These findings demonstrate 1) differential eGL expression of CD2, CD49a, and CD122 during the menstrual cycle; 2) differential IL-2-induced eGL proliferative responses during the menstrual cycle; and 3) differences between eGLs from nonpregnant and pregnant endometrium in CD49d expression and their ability to respond to PHA.
