Selection of patients with habitual abortion for paternal leucocyte immunization

Factors influencing success rate of leukocyte immunization and anti-paternal antibodies in spontaneous recurrent miscarriage

PROBLEM

Paternal leukocyte immunotherapy has been used as treatment for spontaneous recurrent miscarriage; however, controversies have raged against the factors influencing its success.

METHODS

Five hundred and forty-nine women with three or more unexplained pregnancy losses were offered immunization. Two weeks after the second immunization, serum was tested for anti-paternal cytotoxic antibody (APCA) by cross matching and if revealed positive she was advised pregnancy. Meanwhile, decision trees have been developed by Waikato Environment for Knowledge Analysis package to predict factors influencing APCA production and pregnancy.

RESULTS

Of 549 subjects, 93 (16.9%) revealed to have positive APCA, among whom 49(52.7%) had clinically successful pregnancy (> or =28 weeks). Patient's age, consanguinity between couples and previous history of surgery, and infectious, endocrine, immunologic, uterine and cervix disorders were inversely associated with APCA production and clinically successful pregnancy, whilst, number of children was a potent positive predictor.

CONCLUSION

Leukocyte immunization could be borne in mind as a therapeutic approach in selected subjects. Younger females with negative past medical history who are not frequent aborters are more likely to take benefit from this therapeutic approach if they do not have any familial relationship with their spouse.

Thyroid autoimmunity in patients with recurrent spontaneous miscarriages

Recurrent spontaneous miscarriage (RSM) is a multifactorial problem. Auto- and alloimmune parameters have been implicated. Antithyroid antibodies (ATA) were tested in a group of women with RSM. The presence of antipaternal antibodies (APCA) was evaluated as an index of alloimmune contribution. Thirty euthyroid women with RSM (three or more consecutive miscarriages) aged 25-37 years were compared with 15 matched controls. Thyroid peroxidase (TPO) and thyroglobulin antibodies were tested with a chemiluminescence immunoassay and APCA were tested with a cross-match reaction. Results were compared using the chi-squared test. There was a higher frequency of ATA in women with RSM compared to controls (37% versus 13%, p < 0.05). Twenty of the women (67%) with RSM were tested negative for APCA, indicating an alloimmune contribution to their infertility. In this subgroup of women, the frequency of ATA continued to be higher than controls (40% versus 13%, p < 0.05). In conclusion, women with RSM, independent of APCA status, have a higher frequency of ATA. This may represent an additional marker for impaired regulation of the maternal immune system.

Immunologically mediated abortion (IMA)

Roughly 20% of all clinical pregnancies evolve into "spontaneous abortions". The causes of spontaneous abortion have been determined in under 60% of the total and comprise genetic, infectious, hormonal and immunological factors. In some cases the immune tolerance mechanism may be impaired and the foetus immunologically rejected (IMA, immunologically mediated abortion). The immunological mechanism implicated depends on the time in which pregnancy loss takes place. During preimplantation and up to the end of implantation (13th day) the cell-mediated immune mechanism (potential alloimmune etiologies) is responsible for early abortion. This mechanism involves immunocompetent decidual cells (eGL, endometrial granulated lymphocytes) already present during pre-decidualization (late luteal phase) and their production of soluble factors or cytokines. Once the implantation process is over, after blastocyst penetration of the stroma and the decidual reaction of uterine tissue, IMA could be caused by cell-mediated and humoral mechanism (anti-paternal cytotoxic antibodies or autoantibody etiology), by the production of paternal anti major histocompatibility complex antibodies, or even by an autoimmune disorder leading to the production of autoantibodies (antiphospholipid antibodies, antinuclear antibodies or polyclonal B cell activation). The diagnostic work-up adopted to select IMA patients is crucial and includes primary (karyotype of both partners, toxo-test, hysterosalpingography, endometrial biopsy, thyroid function tests, serum hprolactin, luteal phase dating) and secondary (full hemochromocytometric test, search for LE cells, lupus anticoagulant, anticardiolipin, antinuclear antibodies, Rheumatoid factor, blood complement VDRL) investigations. Therapeutical approaches vary. If autoimmune disorders are demonstrated therapies with different combinations of corticosteroids, aspirin and heparin or intravenous immunoglobulin are administered. Otherwise, therapy with paternal or donor peripheral blood mononuclear cells should be instituted.

Effect of paternal leukocyte immunization on implantation after biochemical pregnancies and repeated failure of embryo transfer

PROBLEM

It is unclear how paternal leukocyte immunization prevents pregnancy loss. We investigated whether immunization affects early pregnancy, and whether it increases the rate of implantation and early embryonic development at the time of implantation.

METHOD

Three groups of women with possible implantation failure were immunized: (1) recurrent biochemical pregnancies (> 3), (2) three or more failed in vitro fertilization (IVF) cycles, and (3) IVF after immunization for recurrent abortion (> 3). Patients were immunized if antipaternal complement-dependent antibody (APCA) was negative, and mixed lymphocyte culture hyporeactive to husbands lymphocytes. Immunizations were prepared from 100 ml paternal blood separated by Ficoll Hypaque density centrifugation. IVF was attempted after APCA was produced.

RESULTS

In the women with biochemical pregnancies, 10 to 12 subsequent pregnancies developed normally. Seventy-nine subsequent IVF cycles in 33 patients resulted in 20 pregnancies, 16 of which developed normally. Six pregnancies followed 30 cycles in recurrent failed IVF, and 14 pregnancies from 49 cycles in 23 patients with previous habitual abortion.

CONCLUSIONS

This treatment may prevent further biochemical pregnancies if control studies confirm this preliminary observation, but was not shown to affect recurrent failed embryo transfer.

Immune reproductive failure: effect of nonspecific immunostimulation in mouse model

There is much evidence that pregnancy loss may be immunologically mediated. Failure of the maternal immune system to actively support the pregnancy may be responsible for its demise. Potentiation of immune functions has been attempted in humans; however, the success of immunotherapy is still not clear. Thus immunotherapy experiments in mouse models are important. Nonspecific immuno-stimulation with complete Freund adjuvant (CFA) was shown in our laboratory to reverse the tendency to fetal loss in the CBA/J X DBA/2J mouse combination. CFA elevates the non-T lymphocyte population, decreases T-cell secreted lymphokines, and enhances macrophage-secreted monokines. However, a relationship between these changes and a beneficial effect of CFA on reproductive performance has to be proved. Information obtained from nonspecific immunopotentiation in the CBA/J-DBA/2J model may contribute the assessment of nonspecific immunotherapy in humans.

Anti-idiotypic IgM antibodies to anti-HLA class I antibodies in habitual abortion

In order to investigate the role of the idiotypic network in miscarriages, sera from 28 habitually aborting women undergoing paternal leukocyte immunization were studied for the presence of HLA antibodies and related anti-idiotypes. Sixty-eight percent of sera from preimmunized patients which did not contain anti-lymphocyte antibodies inhibited the activity of antibodies to the HLA class I antigens expressed by the spouse. This inhibitory activity could be assigned to IgM antibodies, which cross-inhibit antibodies of similar specificity. This suggests that they are anti-idiotypes for the binding site of HLA antibodies. Immune sera of successfully treated patients exhibited both cytotoxic IgG anti-HLA antibodies and inhibitory IgM anti-idiotypic antibodies. A possible role for an intact idiotypic network in maintaining pregnancy is suggested.