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John Iacomini

Publications and source records attributed to John Iacomini.

23 records · Page 2Linked to original sources
PubMed2002

The role of T cell help in the production of antibodies specific for Gal alpha 1-3Gal.

The majority of xenoreactive natural Abs in humans recognize the carbohydrate Ag present on pig tissue, Galalpha1-3Galbeta1-4GlcNAc-R (alphaGal), synthesized by the enzyme UDP galactose:beta-D-galactosyl-1,4-N-acetyl-D-glucosaminide alpha(1-3)galactosyltransferase or alphaGT. Using alphaGT knockout mice (GT(0) mice), which like humans produce serum Abs that bind alphaGal, we examined the role of T cells in production of Abs specific for alphaGal. GT(0) mice were crossed with TCR-beta knockout mice (TCR-beta(0)) to generate double-knockout mice (GT(0)/TCR-beta(0)). While GT(0)/TCR-beta+ mice exhibited an age-dependent increase in the serum titer of natural Abs specific for alphaGal, a similar increase was not observed in GT(0)/TCR-beta(0) mice, and the titer of alphaGal-specific Abs in double knockouts was significantly lower than in age-matched GT(0)/TCR-beta+ mice. Immunization with pig cells resulted in a significant increase in the serum titer of alphaGal-specific Abs in GT(0)/TCR-beta+ mice, but had no effect on the level of alphaGal-specific serum Abs in GT(0)/TCR-beta(0) mice. Treatment of GT(0)/TCR-beta+ mice with anti-CD40L Abs before immunization with pig cells prevented sensitization to alphaGal. Our data suggest that the majority of alphaGal-specific Abs are T cell dependent and that production of alphaGal-specific Abs after sensitization can be prevented by blocking costimulatory pathways.

Animals↗
PubMed2002

Engraftment of genetically modified bone marrow cells in sensitized hosts.

Expression of retrovirally transduced genes in bone marrow-derived cells can be used to establish stable long-term B- and T-cell tolerance. To determine whether preexisting antibodies may prohibit the use of gene therapy to establish tolerance, we examined the extent to which preexisting antibodies specific for the carbohydrate antigen Gal alpha1-3Gal beta1-4GlcNAc-R (alpha Gal) could affect engraftment and development of bone marrow progenitors expressing the enzyme UDPgalactose:beta-D-galactosyl-1,4-N-acetyl-D-glucosaminide alpha(1-3)galactosyltransferase (E.C. 2.4.1.151), or simply alpha GT, which synthesizes the alpha Gal epitope. Groups of alpha GT knockout mice (GT(0) mice) lacking alpha Gal were presensitized to alpha Gal by immunization and then lethally irradiated and reconstituted with varying numbers of alpha GT-transduced syngeneic bone marrow cells. Whereas unimmunized controls were reconstituted with as few as 2 x 10(6) transduced cells, a significant fraction of immunized mice reconstituted with 2 x 10(6) or 4 x 10(6) alpha GT-transduced cells failed to undergo bone marrow engraftment and died. Immunized mice in which radiation protection was achieved failed to express alpha Gal. However, radiation protection and expression of alpha Gal on bone marrow-derived cells, resulting in tolerance, could be achieved by increasing the number of transduced cells used to reconstitute immunized mice. Thus, although high levels of preexisting antibodies can be a significant barrier to engraftment, this barrier can be overcome by increasing the number of transduced cells used for reconstitution.

Animals↗
PubMed2002

Defective proliferative responses in B lymphocytes and thymocytes that lack neurofibromin.

Nf1(-/-) fetal liver cells were used to reconstitute B and T cells in Rag-1(-/-) mice. Lymphocyte development was largely unimpaired in the absence of neurofibromin. However antigen-receptor induced proliferation was defective in neurofibromin deficient peripheral B cells and CD4(+) single positive thymocytes. In contrast to its role as a negative regulator of proliferation in many other cell types, neurofibromin may be a positive regulator of lymphocyte proliferation. Peripheral B cells exhibited circumscribed defects in anti-IgM induced protein tyrosine phosphorylation, which may contribute to the unexpected proliferative defect seen in these cells.

Animals↗
PubMedDate not supplied

High efficiency and long-term foreign gene expression in cultured liver sinusoidal endothelial cells by retroviral transduction.

The liver sinusoidal endothelial cells (LSECs) constitute a very specialized endothelium. Due to their multiple functions and privileged location in the liver, these cells constitute an excellent target for gene therapy. In this work, the authors investigate the efficiency of retroviral gene transduction as a method for in vitro gene delivery into murine LSECs. Gene transduction into murine LSECs was performed using the PCMMP-eGFP/pIK-MLVgp retrovirus pseudotyped with the vesicular stomatitis virus G glycoprotein (VSV-g), containing eGFP as a reporter gene. Retroviral transduction resulted in a high efficiency of gene transfer (99%) and stable expression of eGFP in LSECs. The retroviral transduction protocol did not affect the morphology or expression of endothelial cell markers or the biological functions of LSECs. The authors have developed conditions for high-efficiency and stable retroviral gene transduction of LSECs. These results raise the possibility of liver gene therapy using LSECs as vehicle for the delivery of therapeutic proteins by means of retroviral vectors.

Animals↗