Structural and functional comparison of mast cells in the pregnant versus nonpregnant human uterus.
OBJECTIVE
To characterize uterine mast cells and investigate uterine muscle strips contractile responses to challenge with an allergen in nonpregnant and pregnant women.


METHODS
A double-antibody labeling technique was used to identify tryptase positive or chymase-tryptase-positive mast cells in uterine samples from term pregnant and nonpregnant women. Longitudinal myometrial strips were prepared from biopsies of hysterectomy specimens from patients undergoing procedures for benign indications and women who had elective cesarean sections. Responses to ragweed antigen were compared in uterine tissues from allergic and nonallergic patients and with passively sensitized tissues in the absence or presence of H1 receptor antagonist and a cyclooxygenase inhibitor.


RESULTS
Tryptase-chymase-positive mast cells were predominant in nonpregnant myometrium, whereas tryptase-positive cells were dominant in pregnant myometrium. Mast cell density was significantly higher in tissue from pregnant women than those of nonpregnant women. Studies in tissues from patients with known allergy to ragweed, as well as in passively sensitized tissues, showed an immediate and substantial increase in the frequency and force of myometrial contraction after a challenge with ragweed antigen. A similar response was observed to histamine. There was no contractile response to antigen challenge in tissues from nonallergic patients. An H1 receptor antagonist partially inhibited the response to antigen, whereas a cyclooxygenase inhibitor had no effect.


CONCLUSIONS
Sensitized isolated pregnant and nonpregnant human uterine tissue is capable of responding to antigen challenge with strong myometrial contractions. This ability, along with the increased density of mast cells in pregnant tissues as compared with nonpregnant tissues, indicates a possible role for mast cells in mediating uterine contractility in pregnancy.
Garfield
Robert E
RE
Division of Reproductive Sciences, Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston, TX 77555-1062, USA. rgarfiel@utmb.edu
Irani
Anne-Marie
AM
Schwartz
Lawrence B
LB
Bytautiene
Egle
E
Romero
Roberto
R
D031164:Ambrosia / Q000276:immunology; D052179:Antigens, Plant / Q000276:immunology; D016022:Case-Control Studies; D002452:Cell Count; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004155:Diphenhydramine / Q000494:pharmacology; D005260:Female; D006632:Histamine / Q000494:pharmacology; D006634:Histamine H1 Antagonists / Q000494:pharmacology; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology / Q000473:pathology / Q000503:physiopathology*; D007114:Immunization; D007116:Immunization, Passive; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D008407:Mast Cells / Q000473:pathology*; D011247:Pregnancy / Q000502:physiology*; D011248:Pregnancy Complications / Q000276:immunology / Q000473:pathology / Q000503:physiopathology*; D016037:Single-Blind Method; D014590:Uterine Contraction / Q000187:drug effects; D014599:Uterus / Q000187:drug effects / Q000276:immunology / Q000473:pathology* / Q000503:physiopathology*
D052179:Antigens, Plant; D016861:Cyclooxygenase Inhibitors; D006634:Histamine H1 Antagonists; D006632:Histamine; D004155:Diphenhydramine; D007213:Indomethacin