Human reproductive failure I: Immunological factors

Human reproductive failure may be a consequence of aberrant expression of i mmunological factors during pregnancy. Although the relative importance of immunological factors in human reproduction remains controversial, substant ial evidence suggests that human leukocyte antigens (HLA), antisperm antibo dies, integrins, the leukaemia inhibitory factor (LIF), cytokines, antiphos pholipid antibodies, endometrial adhesion factors, mucins (MUC1) and uterin e natural killer cells contribute to reproductive failure. In contrast, few er data support the roles of anti-trophoblast antibodies, anti-endometrial antibodies, T-cells, peripheral natural killer cells, anti-HLA antibodies, blocking antibodies and suppressor cells in reproductive failure, Although immunological factors involved in reproductive failure have been studied tr aditionally using assays for antibodies and/or antigens, detailed research on these factors demonstrates conflicting results in humans. Maternal and f etal immunology is also difficult to investigate in humans. For these reaso ns, molecular assays may serve as a valuable alternative to investigate how the immune system affects reproductive outcome. In Part I of this review, immunological factors involved in human reproductive failure are summarized and critically evaluated. Immunogenetic and interacting factors in human r eproductive failure will be summarized and evaluated in Part II.