IMMUNOLOGICALLY MEDIATED ABORTION (IMA)

Roughly 20% of all clinical pregnancies evolve into ''spontaneous abor tions''. The cause of spontaneous abortion have been determined in und er 60% of the total and comprise genetic, infectious, hormonal and imm unological facors. In some cases the immune tolerance mechanism may be impaired and the foetus immunologically rejected (IMA, immunologicall y mediated abortion). The immunological mechanism implicated depends o n the time in which pregnancy loss takes place. During preimplantantio n and up to the end of implantation (13th day) the cell-mediated immun e mechanism (potential alloimmune etiologies) is responsible for early abortion. This mechanism involves immunocompetent decidual cells (eGL , endometrial granulated lymphocytes) already present dring predecidua lization (late luteal phase) and their production of soluble factors o r cytokines. Once the implantation process is over, after blastocyst p enetration of the stroma and the decidual reaction of uterine tissue, IMA could be caused by cell-mediated and humoral mechanism (antipatern al cytoxic 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 (an tiphospholipid 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, ser um hprolactin, luteal phase dating) and secondary (full emochromocytom etric test, search for LE cells, lupus anticoagulant, anticardiolipin, antinuclear antibodies, Rheumatoid factor, blood complement VDRL) inv estigations. Therapeutical approaches vary. If autoimmune disorders ar e demonstrated therapies with different combinations of corticosteroid s, aspirin and heparin or intravenous immunoglobulin are administered. Otherwise, therapy with paternal or donor peripheral blood mononuclea r cells should be instituted.