Immunoglobulin levels and phagocytes in the cervical mucus plug at term of pregnancy.
BACKGROUND
To characterize the potential for adaptive immune protection in cervical mucus plugs with respect to immunoglobulin isotypes and effector cells (phagocytes).


METHODS
Thirty-one cervical mucus plugs were collected from healthy women in labor at term. The cervical mucus plugs were allocated either to analysis of immunoglobulins by enzyme-linked immunosorbent assay (ELISA), gel chromatography and Western blotting (n = 20) or to microscopical, including immunocytochemical, analyses. The levels of immunoglobulin in the plugs were compared to the levels in 10 samples of ovulatory cervical mucus from nonpregnant women.


RESULTS
In the cervical mucus plugs, levels of immunoglobulin G (IgG) [median 3270 microg/mL (100-14 500)] and IgA [540 (22-2820)], but not IgM [30.5 (1.0-160)], were significantly elevated compared to cervical mucus from nonpregnant women (p < 0.02 for IgG and IgA). The IgG : IgA ratio in the plugs was also elevated (p < 0.02). The proportion of secretory immunoglobulin A (SIgA) relative to total IgA in the plugs ranged from 16 to 65% (n = 5). IgA and IgG were largely intact. Microscopically, the vagina-proximal part of the cervical mucus plugs contained bacteria and was rich in cells, mainly phagocytes. Conversely, the uterine part contained few cells.


CONCLUSIONS
The high immunoglobulin levels in combination with the presence of phagocytes suggest a potential for adaptive immune defense in the cervical mucus plug, which, together with innate immune factors, may act as an immunological gatekeeper protecting the fetomaternal unit against infection from the vagina.
Hein
Merete
M
Department of Obstetrics and Gynecology, Aarhus University Hospital, DK-8200 Aarhus N, Denmark. merete.hein@dadlnet.dk
Petersen
Astrid C
AC
Helmig
Rikke Bek
RB
Uldbjerg
Niels
N
Reinholdt
Jesper
J
D015153:Blotting, Western; D016022:Case-Control Studies; D002582:Cervix Mucus / Q000166:cytology / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007112:Immunity, Maternally-Acquired; D007070:Immunoglobulin A / Q000276:immunology; D007074:Immunoglobulin G / Q000276:immunology; D007075:Immunoglobulin M / Q000276:immunology; D007136:Immunoglobulins / Q000032:analysis / Q000276:immunology*; D007231:Infant, Newborn; D010298:Parity; D010586:Phagocytes / Q000166:cytology*; D011247:Pregnancy / Q000502:physiology*; D012494:Sampling Studies
D007070:Immunoglobulin A; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D007136:Immunoglobulins