Normal human cord blood B cells can produce high affinity IgG antibodies to dsDNA that are recognized by cord blood-derived anti-idiotypic antibodies

Heterogeneous pathways of maternal-fetal transmission of human viruses (review)

Several viruses can pass the maternal-fetal barrier, and cause diseases of the fetus or the newborn. Recently, however, it became obvious, that viruses may invade fetal cells and organs through different routes without acute consequences. Spermatozoa, seminal fluid and lymphocytes in the sperm may transfer viruses into the human zygotes. Viruses were shown to be integrated into human chromosomes and transferred into fetal tissues. The regular maternal-fetal transport of maternal cells has also been discovered. This transport might implicate that lymphotropic viruses can be released into the fetal organs following cellular invasion. It has been shown that many viruses may replicate in human trophoblasts and syncytiotrophoblast cells thus passing the barrier of the maternal-fetal interface. The transport of viral immunocomplexes had also been suggested, and the possibility has been put forward that even anti-idiotypes mimicking viral epitopes might be transferred by natural mechanisms into the fetal plasma, in spite of the selective mechanisms of apical to basolateral transcytosis in syncytiotrophoblast and basolateral to apical transcytosis in fetal capillary endothelium. The mechanisms of maternal-fetal transcytosis seem to be different of those observed in differentiated cells and tissue cultures. Membrane fusion and lipid rafts of high cholesterol content are probably the main requirements of fetal transcytosis. The long term presence of viruses in fetal tissues and their interactions with the fetal immune system might result in post partum consequences as far as increased risk of the development of malignancies and chronic pathologic conditions are discussed.

Biologically active anti-nerve growth factor antibodies in commercial intravenous gammaglobulin

Neurotrophins are regulators of development, survival and function of neuronal and non-neuronal cells, one of the most important of which is nerve growth factor (NGF). Previous studies have demonstrated the presence of antibodies to NGF in normal human serum. It would therefore be predicted that antibodies to NGF would also be present in commercial intravenous gammaglobulin (IVIg). It has been shown in the present investigation that ELISA can detect anti-NGF antibodies in IVIg. The functional activity of these antibodies has been demonstrated after affinity purification, by their inhibitory effects upon (a) the proliferation of the NGF-responsive rat pheochromocytoma cell line PC-12, (b) the differentiation of PC-12 cells as determined by neurite outgrowth. All batches of commercially tested IVIg contained anti-NGF antibodies. Since NGF has an important role in the inflammatory immune response and in cell growth and differentiation, these findings may (a) facilitate our understanding of the mechanisms of action of IVIg, (b) indicate new disease states in which IVIg or its derivatives may exert beneficial effects.

Abnormal germinal center reactions in systemic lupus erythematosus demonstrated by blockade of CD154-CD40 interactions

To determine the role of CD154-CD40 interactions in the B cell overactivity exhibited by patients with active systemic lupus erythematosus (SLE), CD19+ peripheral B cells were examined before and after treatment with humanized anti-CD154 mAb (BG9588, 5c8). Before treatment, SLE patients manifested activated B cells that expressed CD154, CD69, CD38, CD5, and CD27. Cells expressing CD38, CD5, or CD27 disappeared from the periphery during treatment with anti-CD154 mAb, and cells expressing CD69 and CD154 disappeared from the periphery during the post-treatment period. Before treatment, active-SLE patients had circulating CD38 (bright) Ig-secreting cells that were not found in normal individuals. Disappearance of this plasma cell subset during treatment was associated with decreases in anti-double-stranded DNA (anti-dsDNA) Ab levels, proteinuria, and SLE disease activity index. Consistent with this finding, peripheral B cells cultured in vitro spontaneously proliferated and secreted Ig in a manner that was inhibited by anti-CD154 mAb. Finally, the CD38(+/++)IgD(+), CD38(+++), and CD38(+)IgD(-) B cell subsets present in the peripheral blood also disappeared following treatment with humanized anti-CD154. Together, these results indicate that patients with active lupus nephritis exhibit abnormalities in the peripheral B cell compartment that are consistent with intensive germinal center activity, are driven via CD154-CD40 interactions, and may reflect or contribute to the propensity of these patients to produce autoantibodies.

Marked increase in L-selectin-negative T cells in neonatal pertussis. The lymphocytosis explained?

The detailed immunophenotype of peripheral blood lymphocytes from a neonate with pertussis was determined by flow cytometry and compared with results from cord blood from healthy newborns. Most (72%) of the lymphocytes were CD3+ T cells with a normal CD4/CD8 ratio (2.5). The T cells were largely HLA-DR negative and CD45RA+, consistent with unstimulated naïve T cells. Almost all of the CD4+ T cells were Leu8 (L-selectin, CD62L) negative, while almost all of the CD8+ T cells were CD28+. There was no increase in CD7- CD4+ T cells (Th2-like). No relative increase in CD16/56+ NK cells (5%) or CD19/20+ B cells was seen. The most dramatic finding in this case was the remarkable lack of expression of L-selectin by the T cells. L-selectin expression is associated with homing of peripheral blood lymphocytes to lymph nodes. The dramatic reduction in L-selectin expression of the T lymphocytes in pertussis, perhaps induced by pertussis toxin, likely prevents homing of the T cells to peripheral lymphoid tissues and provides a likely explanation for the marked lymphocytosis noted in this disease.

Possible role of interleukin-10 in autoantibody production and in the fate of human cord blood CD5+ B lymphocytes

Mononuclear cell subsets in 25 human umbilical cord blood samples and 10 healthy adults were studied. We found a decreased percentage of CD3+ cells, CD8+ cells and gammadelta T cells in cord blood compared with blood from healthy adults. The CD16+56+ and CD19+CD5+ phenotypes were overexpressed in cord blood. We then measured spontaneous gene expression and the production of interleukin-10 in mononuclear cells from cord blood and adult subjects. Although we found no difference between cord blood cells and those from healthy adults, a tendency towards spontaneous interleukin-10 production was observed in cord blood. Phorbol 12-myristate 13-acetate stimulation revealed that, among lymphocytes, cord blood B cells are the main cellular source of interleukin-10. Finally, we found no evidence of augmented spontaneous apoptosis but an increased bcl-2 gene expression in non-T cells from cord blood. Interleukin-10 might protect CD19+CD5+ B cells from apoptosis by inducing bcl-2 and promoting autoantibody production in this B-cell subpopulation.