جستجوی مقالات مرتبط با کلیدواژه « سلولهای کشنده طبیعی » در نشریات گروه « پزشکی »

Introduction & Undoubtedly reproduction as a means of human survival and recurrent spontaneous abortion being the most prevalent complication of pregnancy with a three percent outbreak and an influential problem on human life have always been the subject of interest among researchers. Different factors are involved in recurrent spontaneous abortion among which immunological disorders are considered the most important ones. Immune cells in uterine endometrium specially natural killer (NK) cells at the menstrual cycle and during pregnancy change considerably indicating their important role in reproductive cycle. The aim of the present study was to investigate and compare NK cells in the peripheral blood of nonpregnant women with recurrent abortion، and non pregnant women with normal pregnancy on the basis of flow cytometry development technology and availability of monoclonal antibodies. In a case-control study 30 samples of peripheral blood from nonpregnant women that had three or more consecutive spontaneous abortion with no other medical problems and anatomical disorders (patient group) were obtained. 30 samples of peripheral blood from normal nonpregnant women (control group) were also obtained. All blood samples، after lysis of red blood cells، were stained with two type of monoclonal antibodies; anti CD16 and anti CD56 (NK cell specific markers) and then analyzed by flow cytometry. The data from the two groups were compared using t test. NK cells significantly increased in women with recurrent abortion compared with normal nonpregnant women indicating significant differences in the mean average of CD56+CD16+ population between the patient group and control group (P =0. 026). The mean average of two CD56+ and CD16+ populations significantly increased in the patient group in comparison with the control group (P<0. 05). The increase of NK cells in peripheral blood followed by cytotoxicity function of the cells، particularly in relation to emberyo trophobast cells at the pregnancy cycle، can contribute to the recurrent abortion etiology. More investigations including studying the function of these cells، secretory cytokines and their receptors in recurrent abortion، and other disorders of reproductive system such as infertility، endometriosis، preeclampcia are suggested.

Recurrent spontaneous abortion (RSA) is defined as three or more consecutive miscarriages, which affects 0.8 to 1% of pregnant women. Despite several well-established etiologic factors, the cause of RSA cannot be determined in almost 60% of the cases. It has been postulated that a part of these repeated pregnancy losses might be due to immune causes.

In the present case control study using flowcytometry, peripheral NK cytotoxicity was compared in three different groups. 21 women with history of RSA at the time of 3rd or higher abortion (Group I), 32 women with history of three or more previous abortions and at least three months had lapsed since the last abortion (Group II) and 32 pregnant women with no history of abortion and at least one successful pregnancy (Group III) were studied.

Group I and Group II showed significantly higher NK cytotoxicity than Group III in all of the effect to target (E: T) ratios (P≤0.045 and P≤0.002 respectively). NK cytotoxicity was similar in groups I and II. There were no significant correlation between the number of abortions, age and NK cytotoxicity.

The results indicate an increased peripheral NK cell cytotoxicity in RSA groups as compared to pregnant control. NK cell cytotoxicity may be considered as a risk factor for RSA and for maintaining normal pregnancy, NK cell cytotoxicity may be down-regulated. Peripheral NK cytotoxicity is not elevated during first trimester in RSA women. It is suggested that detection of NK cytotoxicity in RSA women should be performed as a routine.

Natural killer(NK) cells are defined as effector cells that have the capacity of spontaneous cytotoxicity toward various target cells and are not major histocompatibility complex(MHC) restricted. NK cells are the first line of immune system defence and serve in surveillance of certain tumor and virus-infected cells. The aim of this study was to determine CD16++CD56+ marker(NK cells) in healthy Iranian population. Peripheral blood samples of 500 male and female subjects, from different age group(18-60 years), were obtained. Flowcytometry technique with dual color monoclonal antibodies (CD16++CD56+) against NK cells was used to analyse the samples. Statistical analysis was done through SPSS software. The mean of CD16+CD56+ was found to be 15.93±7.02 for male and 13.30±5.89 for female population(P<0.05). The mean ranges of NK cells in different age group in the combined population were significantly less in the subjects aged 31-40 years as compared with subjects aged 50-60 years(P<0.001). Study and determination of NK cells in the peripheral blood indicates that sex, age and race should be a consideration in the evaluation of the immune system. Therefore, the results of the present study can be used in Iran laboratories and research centers to evaluate infectious diseases, tumors and other diseases.