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E S Vitetta

Publications and source records attributed to E S Vitetta.

At least 199 records · Page 11Linked to original sources
PubMed1985

A ricin A chain-containing immunotoxin that kills human T lymphocytes in vitro.

An immunotoxin specific for human T lymphocytes was prepared by coupling an IgG2a anti-CD3 murine monoclonal antibody (64.1) to purified ricin A chain (64.1-A). Treatment of blood mononuclear cells with this immunotoxin at a concentration of 1.7 X 10(-9) mol/L for two hours at 37 degrees C in the presence of 20 mmol/L NH4Cl decreased phytohemagglutinin-stimulated protein synthesis by 95%. In addition, a sensitive culture assay showed that fewer than 0.03% T cells remained after treatment of human bone marrow mononuclear cells with 64.1-A at a concentration of 1.7 X 10(-9) mol/L. The inhibition of protein synthesis could be prevented by preincubating cells with unconjugated 64.1 antibody but not by preincubating cells with a control IgG2a antibody that binds to a different T cell antigen (CD5). At concentrations up to 1 X 10(-8) mol/L, 64.1-A had little effect on blood mononuclear cells from baboons or human myeloid precursors (CFU-GM), which do not express the CD3 antigen recognized by 64.1. Taken together, these results indicate that the toxicity of 64.1-A was specific and that 64.1-A may be a useful reagent for depleting T cells from donor marrow as a means of preventing acute graft-v-host disease after allogeneic bone marrow transplantation.

Ammonium Chloride↗
PubMed1985

The effect of T cell-derived lymphokines on the levels of isotype-specific RNA in normal B cells.

T cell-derived lymphokines, known as B cell differentiation factors (BCDF), play a critical role in the regulation of B cell differentiation. These BCDFs are present in the supernatants (SN) of a long-term alloreactive T cell line, PK 7.1. In this report we present evidence that B cells cultured with lipopolysaccharide (LPS) and BCDFs express increased levels of both the secreted and membrane forms of gamma 1 mRNA. The appearance of mRNA for the membrane form of mu precedes the appearance of mu secreted form mRNA. Approximately 1 day later, appearance of membrane and secreted forms of gamma 3 and gamma 1 can be detected with the membrane forms of both isotypes peaking earlier than the corresponding secreted forms. The mRNAs for both the membrane and secreted forms of gamma 3 are suppressed in the presence of LPS and PK 7.1 SN while LPS alone induces an increase in both. Quantification of newly synthesized nuclear and cytoplasmic RNA for mu, gamma 3, and gamma 1 RNA suggests that PK 7.1 SN down-regulates levels of gamma 3 RNA by decreasing its transcription. In contrast, it may increase level of gamma 1 RNA by effects exerted at the post-transcriptional level. Taken together, these results demonstrate that T cell-derived lymphokines can act on B cells by regulating the levels of nuclear and cytoplasmic RNA specific for gamma 1 and gamma 3.

Animals↗
PubMed1984

Clonal analysis of B cells induced to secrete IgG by T cell-derived lymphokine(s).

To gain insight into how T cell-derived lymphokines induce the secretion of IgG in activated B cells, we performed a limiting dilution analysis, using murine splenic B cells incubated with lipopolysaccharide (LPS) and a T cell-derived B cell differentiating factor for IgG (BCDF gamma)-containing supernatant (SN). The results of this analysis indicate that such a SN induces a marked increase in the precursor frequency of IgG1-secreting cells and a modest increase in clone size. The precursors lack surface IgG and are committed to the differentiation pathway for IgG1 secretion after LPS activation, but before the addition of BCDF gamma-containing SN. The majority of IgG1-secreting clones arise independently from precursors of cells that secrete IgG3. Taken together, these results indicate that BCDF gamma directs differentiation of activated B cells to IgG1 secretion.

Animals↗
PubMed1984

Cytotoxicity of a cell-reactive immunotoxin containing ricin A chain is potentiated by an anti-immunotoxin containing ricin B chain.

In vitro killing of the human Daudi cell line by either univalent [F(ab')] or divalent (IgG) forms of rabbit anti-human Ig (RAHIg) coupled to ricin A chain can be specifically potentiated by a "piggyback" treatment with ricin B chain coupled to goat anti-rabbit Ig (GARIg). When cells are treated with univalent immunotoxin (IT) [F(ab') RAHIg-A] and then cultured, IT can be detected on the cell surface for at least 5 h, since GARIg-B can still enhance killing at this time. These results provide a strategy for in vivo use of A chain- and B chain-containing IT.

Adjuvants, Immunologic↗
PubMed1984

H-40, an antigen controlled by an Igh linked gene and recognized by cytotoxic T lymphocytes. I. Genetic analysis of H-40 and distribution of its product on B cell tumors.

C.B-20 ( Ighb ) mice challenged with BALB/c ( Igha ) spleen cells (or vice-versa) generate cytotoxic T lymphocytes (CTL) that recognize an antigen, H-40, controlled by an Igh-linked gene. The gene maps to the Igh-C region end of the Igh complex, telomeric to Tsu in the region of Pre-1. At least three alleles, a, b, and c, can be defined. Using a cold target competition assay, no polymorphism of the a allele was detected. Both surface Igh-5a positive and negative spleen cells from (C.B-20 X BALB/c)F1 animals express the a allele of the antigen, indicating that this gene is not allelically excluded. Recognition of the target antigen by CTL is restricted by the D-end of H-2d. The tissue distribution of H-40 was explored using both bulk-cultured and cloned CTL. The antigen is expressed on surface immunoglobulin positive (sIg+) cells and correlates with the expression of sIgM. This was determined by analysis of several B lymphomas as well as of other tumors that varied in their extent of expression of sIg. Four subclones of BCL1 were analyzed. Two of the subclones are sIg+ and express H-40, while two other subclones are sIg- and H-40-. Thus, these data define an Igh-linked gene, separate from immunoglobulin structural loci, that controls an antigen expressed on sIg+ cells. Possible mechanisms to account for this finding are discussed.

Alleles↗
PubMed1984

In vivo reconstitution of ricin-like activity from its A and B chain subunits.

The capacity of highly purified preparations of ricin A and B chains to reconstitute ricin toxicity both in vitro and in vivo was studied. When the nontoxic A and B chain subunits were mixed and electrophoresed on sodium dodecyl sulphate-polyacrylamide gels (SDS-PAGE), reconstituted ricin was observed. The mixtures killed cells of the human Burkitt's lymphoma cell line Daudi in vitro and killed mice after i.v. injection. It was also shown that when mice were injected with one ricin subunit followed by administration of the complementary polypeptide up to 8 hr later, they died with lesions similar to those of ricin-induced death. This observation suggests that A and B chains recombine either in the serum or on the surface of cells. The rate of clearance of A and B chains from the blood of rats indicated that sufficient concentrations of either chain were present in the circulation 8 hr after injection to account for the observed toxicity. The above studies therefore suggest that the subunits of ricin have a very high affinity for each other and are capable of reconstituting biologically active ricin in vitro and in injected mice.

Animals↗
PubMed1984

Increased expression of Ia antigens on resting B cells: an additional role for B-cell growth factor.

The present studies demonstrate that both T-cell-derived supernatants containing B-cell growth factor (BCGF or BSF) and a partially purified preparation of the B-cell growth factor (BSF-p1) induce an increase in the expression of IA and IE-encoded antigens on small resting B cells. This increase is detectable by 6-8 hr after initiation of culture and is relatively selective, since levels of surface immunoglobulin and H-2 antigens do not increase to the same extent. Although interferon-gamma induces increased expression of Ia antigens on macrophages and dividing neoplastic B cells, it does not induce an increase in the expression of Ia antigens on resting B cells. These results demonstrate that BSF-p1 may play two roles: (i) it acts on resting B cells to increase the levels of Ia antigen expression; and (ii) it sustains the growth of B cells that have been previously activated with mitogens, antigens, or anti-Ig.

Animals↗
PubMed1984

A B cell growth factor-like activity is secreted by cloned, neoplastic B cells.

Supernatants from synchronized clones of neoplastic B cells (BCL1) were found to contain a B cell growth factor (BCGFI)-like activity. The BCGF activity in the BCL1 supernatants (SN) could synergize with EL-4 SN in the late phases of an IL 1-dependent BCGF I assay (days 5 through 8). These SN did not contain any detectable BCGF II, IL, 1, or IL 2 activity. In contrast to EL-4-derived BCGF I, which has a m.w. of approximately 18,000, the BCL1-BCGF activity has a m.w. of approximately 4500. Because the BCGF activity in BCL1 SN fluctuates with cell cycle in synchronized cultures, this BCL1-BCGF may play an auto-stimulatory role in B cell proliferation.

Animals↗
PubMed1984

sIgD-negative B cells from neonatal mice do not respond to the thymus-independent antigen TNP-BA in limiting dilution cultures.

The majority of B lymphocytes in adult mice express both IgM and IgD on their surface (sIgM and sIgD). A small percentage of sIgM+ splenic B cells lack (or express very low levels of) sIgD. These cells have been termed "mu-predominant" (mu p) B cells. In neonatal mice (5 to 12 days of age), mu p B cells account for more than 50% of the sIg+ cells. There is conflicting evidence concerning the immunocompetency of mup cells in vitro. To study this question further, splenocytes from neonatal BALB/c mice were depleted of sIgD+ B cells by a panning procedure. A portion of the nonadherent (mu p) cell population was analyzed for residual sIgD+ cells by using indirect immunofluorescence in conjunction with the fluorescence-activated cell sorter (FACS). Such cells were then tested for their responsiveness to the thymus-independent (TI) antigen, trinitrophenyl Brucella abortus (TNP-BA), by using a limiting dilution culture system. Results indicate that the depletion of sIgD+ B cells and the decrease in the precursor frequency of splenocytes responding to TNP-BA are very similar, suggesting that virtually all of the responding B cells bear sIgD.

Animals↗
PubMed1984

Role of surface immunoglobulin in B lymphocyte activation.

Studies of polyclonal and antigen-specific activation of B lymphocytes were compared to generate a model that addresses the roles of ligand-surface (s) IgD and ligand-sIgM interactions as well as the roles of antigen-specific, T cell-mediated help and nonspecific helper lymphokines in the activation of mature, resting B lymphocytes. The major features of the model are 1) cross-linking of sIg renders B cells more receptive to T cell help; 2) DNA synthesis in activated B cells can be induced by weak sIg cross-linking signals in the presence of antigen-specific T cell help or by stronger sIg cross-linking signals in the absence of help; 3) sIgD has a more dominant role than sIgM in direct, sIg-mediated B cell activation whereas sIgM has a more dominant role than sIgD in focusing antigen-specific T cell help onto activated B cells; 4) the loss of sIgD from activated B cells limits the transmission of sIg-mediated signals that can inhibit the differentiation of B cells into antibody-secreting cells; and 5) the cross-linking of sIg, the focusing of antigen-specific T cells, and nonspecific helper lymphokines are all required for induction of rapid, effective antibody responses against bacterial pathogens.

Animals↗
PubMed1983

Lymphokine-induced IgM secretion by clones of neoplastic B cells.

The induction of antibody secretion by B cells requires T-cell-derived factors1-5. Such factors have been described1,2,6-12 but the precise relationship among these various factors is not clear, and it has been difficult to demonstrate that these factors act directly on the B cell and do not exert their effect via T cells or macrophages. In this report we describe the direct induction of IgM synthesis and secretion in cloned lines of long-term tissue culture adapted neoplastic B cells (BCL1) by T-cell supernatants from phorbol-12-myristate 13-acetate (PMA)-induced EL-4 cells or concanavalin A (Con A)-induced 7.1.1a cells5,9. We have termed this activity BCDFmu (B-cell differentiation factor for IgM). The supernatants containing BCDFmu induce activated and neoplastic B cells to secrete IgM5 and the factor responsible is distinct from BCGF13, interleukin-2 (IL-2)5, the classical T-cell replacing factor (TRF) described by Schimpl and Wecker5, and immune interferon (IFN gamma)5.

B-Lymphocytes↗