Immunomodulation and remyelination: two aspects of human polyclonal immunoglobulin treatment in immune mediated neuropathies?

Effect of intravenous immunoglobulin treatment on the Th1/Th2 balance in women with recurrent spontaneous abortions

PROBLEM

The way by which intravenous immunoglobulin (IvIg) acts to prevent immunlogically mediated recurrent spontaneous abortions (RSA) has not been clarified. In the present study, a possible effect of IvIg on the T helper cell (Th1/Th2) balance was investigated in abortions of either alloimmune or autoimmune abnormalities.

METHOD OF STUDY

The study included 21 women treated with IvIg before conception because of a history of RSA characterized by alloimmune abnormalities (n = 15) or associated with anti-phospholipid antibodies (APA) (n = 6). Peripheral blood samples, collected before and 5 days after the first IvIg infusion, were stimulated, and Th1 and Th2 cells were detected by flow-cytometric analysis using a combination of monoclonal antibodies against T-cell surface markers and intracellular interferon (IFN)-gamma and interleukin (IL)-4. The percentage of IFN-gamma-producing (Th1) and IL-4-producing (Th2) cells and the Th1/Th2 ratio were compared between pre- and post-infusion samples.

RESULTS

A decrease of Th1 percentage in 66.6% of the cases and a concurrent Th2 percentage increase (47.61%) resulted in a decrease in the Th1/Th2 ratio in most of the cases (76.1%) (p < 0.01). Similar results were found in Group A (Th1/Th2 decreased in 60% of the cases, p < 0.05), while in Group B the effect of IvIg was not clear (Th1/Th2 increased in three and decreased in another three cases).

CONCLUSION

Our finding suggests that IvIg administration in women with alloimmune RSA enhances Th2 polarization. This is not always the case with APA-associated abortions.

IVIG-pools: regulatory gifts--transiting from harmony toward harmonious immunoglobulins: why? and why not?

Based on 'initial conditions' which depend on each donors' exposure to a unique environment, a pooled intravenous immunoglobulin (IVIG) product transfers its immunoglobulin molecule repertoire, unchanged, to the altered host. The relay function of the cell-bound receptors, especially that of the inhibitory Fc(gamma)RIIB, may then allow sufficient amplification to make regulatory activity possible. To the clinician, IVIG may be considered a tool to promote reversal of the dysregulation causing autoimmune disease. Generically, IVIG may be seen as a promoter allowing a progression from harm by an inflammatory/fibrotic reaction, then down-regulating toward restitutio ad integrum. By modifying natural processes, IVIG may play minor roles in promoting defense against spontaneous bleeding and, perhaps, stimulating remyelination. The wide spectrum of IVIG specificities, by reflecting evolutionary epitope selection, may not further destabilize cell/molecule disarray in the affected host. Benefit to the patient by IVIG treatment cannot be predicted nor can potentially severe or even fatal accidents entirely be excluded. Important aspects of IVIG treatment still await clarification including dosage, timing and the isotype form. In the foreseeable future it does not seem that biotechnological advances will match the physiologic harmony of IVIG, leaving antibody characteristics aside.

Human polyspecific immunoglobulin for therapeutic use induces p21/WAF-1 and Bcl-2, which may be responsible for G1 arrest and long-term survival

High-dose intravenous immunoglobulin (IVIg) is used as therapy in an increasing number of immune mediated disorders including infections and autoimmune conditions. IVIg exerts profound effects both in vivo as well as in vitro on humoral and cell-mediated immunity. In this study we investigated whether IVIg could alter the pattern of apoptosis and apoptosis related proteins including Bcl-2, Bax, p53, CD95, and p21/WAF-1, a protein well known to arrest cells in G1 phase of the cell cycle and finally proliferation marker Ki-67 on peripheral blood mononuclear cells (PBMC). The cells were cultured either unstimulated or with mitogen in the presence or absence of different IVIg preparations. A dual effect by IVIg was found. The incidence of apoptosis was elevated in activated Ki-67 and CD95 positive PBMC, whereas it was lower in small, nonactivated cells. The cells that survived were associated with a striking increase in the expression of p21/WAF-1 suggesting G1 arrest. A concomitant upregulation of Bcl-2 was also obtained by IVIg exposition resulting in long-term survival. We suggest that these abilities of IVIg to alter cell cycle progression and apoptosis could explain some of the beneficial effects obtained in vivo with IVIg therapy.

Natural antibody-induced intracellular signalling and growth control in C3H 10T1/2 fibroblast variants

Cell-surface binding by natural antibody (NAb) places it well for controlling cell function directly through signalling. Flow cytometry revealed an instability of syngeneic NAb binding to C3H 10T1/2 fibroblast variants at 37 degrees, which could be partially reduced by H7, an inhibitor of the pivotal signalling serine/threonine kinase, protein kinase C (PKC). Cells coated with purified NAb at 4 degrees followed by a rise in temperature to 37 degrees showed an increase in membrane expression of introduced rat PKC-beta 1 and endogenous PKC-alpha, in the PKC-beta 1-overexpressing PKC-4 and v-H-ras-producing I3T2.1, respectively. Tyrosine phosphorylation of membrane-associated 60 000 MW protein including the tyrosine kinase src was markedly reduced. In addition, both the precoated NAb and numerous membrane molecules ranging from 20,000 to 220,000 MW were released into the supernatant, including the receptor-like protein tyrosine phosphatase alpha (RPTP-alpha). Furthermore, purified NAb reduced the growth of I3T2.1 cells in culture assessed as a decrease in total cell numbers and an increase in the proportion of cells in the G0/G1 phase of the cell cycle. Together, these data argue that the interaction of NAb with cell surface structures initiated a series of intracellular signalling events leading to the release of membrane molecules and over time the suppression of cell proliferation. This process could provide a biological mechanism for direct NAb control of activated cells in both physiological and pathological conditions.

Protein kinase C expression links natural antibody binding with surveillance of activated and preneoplastic cells

Extensive evidence supports a role for natural antibody (NAb) acting against small tumour foci in vivo. Ras-transformation of murine C3H 10T 1/2 fibroblasts, known to partially activate and down-regulate endogenous PKC-alpha, increased their serum NAb-binding capacity consistent with the requirements for natural immune surveillance. Now a rat PKC-beta1-overexpressing 10T 1/2 clone, PKC-4, with an 11-fold increase in PKC activity and an activated, partially transformed phenotype, links higher susceptibility to transformation through v-Ha-ras infection with an 80% increase in NAb binding assayed by flow cytometry. H7 and E-64d inhibition and phorbol ester depletion of PKC reduced NAb binding. PKC-beta1 expression and NAb binding exhibited a similar temporal recovery from TPA treatment. Thus, expression of NAb-binding structures appears to be elevated by constitutive increases in the basal activation of PKC in both the ras-transformation and the PKC-beta1-preneoplasia models. This, coupled with corresponding decreases in membrane PKC-alpha and NAb binding in confluent 10T 1/2 cells raises the possibility that in general, cells activated through PKC are NAb sensitive. Together with the increased in vivo elimination of the high NAb-binding PKC-4 cells, the data extend the support for a role for NAb in immune surveillance, to resistance against preneoplastic cells, and argue for NAb contributing to homeostasis of the organism.