Intravenous immunoglobulin (IVIg) is a safe remedy for a number of conditions; it is produced from human plasma of thousands of healthy donors. The therapeutic effect of IVIg lies within its content. IVIg contains natural antibodies, which are more polyreactive than immune antibodies, including immunoglobulin G antibodies against endogenous and exogenous antibodies, immunomodulating peptides, and varies cytokines. Beneficial effects of IVIg have been established in immunodeficiencies, as well as in some autoimmune diseases. Also, numerous therapeutic effects of IVIg have been reported over the years in varies autoimmune diseases, recurrent pregnancy loss, and cancer. Many proposed immunoregulatory mechanisms of action of IVIg have been suggested. Some of them have been proven, others are still an enigma, at least in part. Some of these mechanisms entail (a) Fc-receptor blockade; (b) neutralization of pathogenic autoantibodies via idiotypic and anti-idiotypic antibodies; (c) effects on the Fas apoptotic pathway via agonistic and antagonistic anti-Fas autoantibodies; (d) regulation of complement components; (e) modulation of cytokine secretion; (f) hindrance of natural-killer cell activity; (g) inhibition of matrix metalloproteinase-9; (h) suppression of NFkB activation and IkB degradation; (i) G1 cell cycle arrest; (j) prevention of tumor growth; (k) decrease in leukocyte recruitment; (l) attenuation of T-cell stimulation; (m) effects on antibody kinetics; and (n) effects on dendritic cells. The variant mechanisms of IVIg are believed to cooperate in a synergistic way, which all together point to IVIg as a therapeutic preparation with anti-inflammatory, antiself-reactivity, antimetastatic, and embryo-protective effects. This article reviews several main mechanisms of IVIg in order to shed some light on the set of therapeutic effects of IVIg, which are not yet fully understood.

Infections can act as environmental triggers inducing or promoting autoimmune disease in genetically predisposed individuals. Identification of microbial peptides similar to self-tissues may by molecular mimicry, provide the inducing mechanism for an immune response. The aim of this study was to identify autoantibodies (autoAbs) in nonautoimmune individuals during acute bacterial, viral, or parasitic infections. Specific Abs or specific infections with an increased autoAb load may shed insight into the mechanisms of autoimmune disease. Sera from 88 patients with acute infections (41 bacterial, 23 viral, 17 parasitic, and 7 rickettsial) were tested by the ELISA method for antinuclear antibodies (ANA) 8 Pro, and Abs to thyroid peroxidase (TPO), thyroglobulin, phospholipids, annexin-V, laminin, anti-Saccharomyces cervisiae (ASCA), and prothrombin, along with 80 normal controls. Elevated titers of Abs to annexin-V and prothrombin were the most prevalent in viral, parasitic, and rickettsial infections and to laminin in viral and parasitic infections. Elevated titers of ASCA and ANA were found in viral and bacterial infections. Antiphospholipid Abs were found in parasitic and Q-fever infections. Thirty-four individuals harbored elevated titers of at least two Abs. An autoAb burden was detected in individuals with hepatitis A, hepatitis B, toxoplasma or Q-fever infections. In nonautoimmune individuals with various (bacterial, viral, parasitic, and rickettsial) infections, elevated titers of Abs to annexin-V, prothrombin, laminin, ASCA, ANA, and phospholipids were most frequently detected.

Intravenous immunoglobulin (IVIG) is a safe preparation, made of human plasma of thousands of healthy donors. The fascinating history of gamma globulin therapy begins in 1930 when Finland treated pneumococcal pneumonia patients with equine serum, which prolonged their survival from pneumonia. Since then, significant breakthroughs were achieved by Cohn, Bruton, Imbach, and others, whose clinical contribution to the world of medicine was of great importance. Originally IVIG was used to treat immunodeficiencies. Later on the use of IVIG extended to autoimmune diseases as well. The efficacy of IVIG has been established only in several autoimmune diseases; clinical reports of trials, series, and case reports indicate significant improvement in many more autoimmune diseases. IVIG have also showed antimetastatic effects in a variety of cancer cell lines, as well as in a few case reports. The efficiency of IVIG has also been observed in recurrent pregnancy loss (RPL), either as a result of an autoimmune disease or spontaneous. Several attempts were made to discover the immunomodulatory effects of IVIG, but it is still not fully understood. Clearly IVIG has multiple mechanisms of actions, which are thought to cooperate synergistically. One of the main mechanisms of actions of IVIG is its ability to neutralize pathogenic autoantibodies via anti-idiotypic antibodies within IVIG preparation. The ability of IVIG to neutralize pathogenic autoantibodies is of great importance in many autoimmune diseases, as well as in RPL. In cancer cell lines, IVIG modulates the immune system in a few ways, including the induction of IL-12 secretion, which consequently activates natural killer cells, and the induction of expression of proapoptotic genes only in cancer cells. Side effects from IVIG are rare and mostly mild and transient. More importantly adverse effects can be minimized by administration to a selective patient population in a proper way: slow infusion rate of 0.4 g/Kg body weight IVIG for 5 consecutive days, given in monthly cycles. The only downside of IVIG therapy is its high price. Therefore, clinicians should balance efficiency versus cost in deciding whether or not to treat certain conditions with IVIG.