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Biomedical subjects

S Dray

Publications and source records attributed to S Dray.

At least 37 records · Page 2Linked to original sources
PubMed1985

Allogeneic lymphocyte stimulation in rabbits: induction of a low MW inhibitor for trypsin and for a concurrently induced alpha-macroglobulin-proteinase complex.

We have shown previously that the i.v. inoculation of allogeneic lymph node cells in rabbits induces the appearance in the serum of an alpha M-serine proteinase complex which behaves in an Ig-turnover assay as any polyclonal B-cell activator (PBA), and that this PBA activity is due to the enzyme. Here, we show that the allogeneic stimulation also induces the appearance in the low molecular weight fraction of the serum (1000-110,000 MW) of an inhibitor which blocks the PBA activity of the complex without affecting the PBA activity of LPS or dextran sulphate. The inhibitor blocked the ability of the enzyme associated with alpha M to degrade Chromozym TRY, a low MW trypsin substrate. The inhibitor also blocked the enzymatic activity of trypsin for large as well as for low MW substrates. Thus, allogeneic stimulation in vivo results in the production, not only of an alpha M-proteinase complex, but also of an inhibitor for this proteinase as well as for trypsin. The appearance of the inhibitor, along with the alpha M-serine proteinase complex as a result of allogeneic stimulation in rabbits, is of interest since a similar alpha M-serine proteinase complex and inhibitor may appear in the serum of patients with rheumatoid arthritis.

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PubMed1984

Melphalan-mediated potentiation of antitumor immune responsiveness of immunosuppressed spleen cells from mice bearing a large MOPC-315 tumor.

Administration of a low dose of L-PAM (0.75 mg/kg) to mice bearing a large SC MOPC-315 tumor and extensive metastases led to the development of augmented antitumor immune potential in their hitherto immunosuppressed spleen cells. Such drug-induced potentiation of antitumor immune responsiveness appeared by day 2 after chemotherapy, and it could not be further enhanced but was actually reduced by depletion of glass-adherent cells, a procedure which is effective in depleting the cells known to have inhibitory activity (i.e., macrophages and metastatic tumor cells). To establish that L-PAM can lead to selective in situ abrogation of the inhibitory effectiveness of the splenic macrophages and metastatic tumor cells, we demonstrated that incubation of immunosuppressed tumor-bearer spleen cells with a low concentration of L-PAM in vitro also resulted in augmented antitumor immune potential that could not be further augmented by depletion of glass-adherent cells. L-PAM-mediated enhancement of the antitumor immune potential of immunosuppressed tumor bearer spleen cells was due at least in part to the effects of the drug on the splenic metastatic tumor cells. Isolated tumor cells treated with a low concentration of L-PAM were not only devoid of inhibitory activity for the primary in vitro antitumor immune response by normal spleen cells, but actually manifested a strong immunostimulatory capacity. Thus, L-PAM given at a low dose enhances the development of potent antitumor immunity which brings about the eradication of a large tumorigenic load that remains after the drug has been cleared from the circulation.

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PubMed1984

Suppression of antitumor immunity by macrophages in spleens of mice bearing a large MOPC-315 tumor.

We had shown previously that progression of MOPC-315 plasmacytoma growth is associated with an increase in the percentage of macrophages in the spleen as well as a decrease in the ability of tumor-bearer spleen cells to mount an antitumor cytotoxic response upon in vitro immunization. Here we provide evidence that macrophages in the MOPC-315 tumor-bearer spleen are responsible at least in part for the suppression of the generation of antitumor cytotoxicity. Accordingly, removal of most macrophages by depletion of phagocytic cells or Sephadex G-10-adherent cells from spleens of mice bearing a large tumor resulted in augmented antitumor immune potential. Also, Sephadex G-10-adherent spleen cells from tumor-bearing (but not normal) mice drastically suppressed the in vitro generation of antitumor cytotoxicity by normal spleen cells. The suppressive activity of these adherent cells did not reside in contaminating suppressor T cells, since it was not reduced by treatment with monoclonal anti-Thy 1.2 antibody plus complement. The Sephadex G-10-adherent cell population from the tumor-bearer spleen suppressed the in vitro generation of antitumor cytotoxicity against autochthonous tumor cells but not against allogeneic EL4 tumor cells, and hence the suppression was apparently specific. The suppressive activity of the Sephadex G-10-adherent cell population from tumor-bearer spleens was overcome by treatment of the tumor-bearing mice with a low curative dose of cyclophosphamide. This immunomodulatory effect of a low dose of the drug in overcoming the suppression mediated by the Sephadex G-10-adherent cell population enables the effector arm of the immune system of tumor-bearing mice to cooperate effectively with the drug's tumoricidal activity in tumor eradication.

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PubMed1984

Induction of "latent a2" allotype in a1a1 homozygous rabbits as the major part of a bidirectional immune response to immunization with anti-a2 antibody.

Previously, we induced Ab to a common idiotypic specificity (IdC) of rabbit anti-a2 VH Ab. We observed then that some of the putative anti-IdC Ab molecules induced by immunizing a1a1 rabbits with anti-a2 Ab did not have the expected nominal allotypic markers (a1, x32, or y33) characteristic of the genotype of the immunized rabbits. Thus, immunization of a1 a1 rabbits with a1 anti-a2 Ab induced population of molecules that reacted with anti-a2 Ab but bore an unidentified (unknown) VH region marker. The following observations indicate that these molecules bear a "latent a2" allotypic marker: (a) when the unknown VH molecules were used to immunize a1 a1 and a3 a3 rabbits, anti-a2 Ab was produced; (b) when an a2 a2 rabbit was immunized with the same preparation of unknown VH molecules, an anti-idiotypic Ab was produced; and (c) when the unknown VH molecules were used to inhibit the binding of labeled a2 IgG to anti-a2 Ab, the inhibition curve obtained was essentially the same as that obtained by using normal a2 IgG. Thus, immunization of a1 a1 rabbits with a1 anti-a2 Ab provided a bidirectional stimulus to produce both nominal "a1" anti-IdC Ab and a "latent a2" allotype. The distribution of nominal to latent allotypes induced ranged from 3% nominal/92% latent to 57% nominal/23% latent. In absolute terms, the maximum amount of "latent a2" molecules was 1.18 mg/ml of serum, which far exceeds the amount of latent allotype described by others (0.3 mg/ml of serum). The effective induction of large amounts of "latent a2" allotype may have resulted from a simultaneous stimulation of an idiotope and a paratope on the surface of the "latent a2"-producing cells.

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PubMed1983

Increase in the effectiveness of melphalan therapy with progression of MOPC-315 plasmacytoma tumor growth.

Following inoculation with 1 X 10(6) MOPC-315 tumor cells, a single injection of a very low dose of melphalan (L-PAM, L-phenylalanine mustard), 0.75 mg/kg, cured most of the mice bearing a day 11 large primary tumor (20 mm) and metastases, but failed to cure mice bearing a day 4 nonpalpable tumor. Treatment of mice bearing a nonpalpable tumor with the very low dose of drug compromised the ability of the mice to respond effectively to the same low dose of drug when the tumor became large (day 12). However, a nonpalpable tumor could be eradicated by treatment of tumor bearers with a low dose of L-PAM, if it was present concomitantly with a large tumor on the contralateral side. A high dose of L-PAM, 15 mg/kg, cured mice bearing either a nonpalpable or a large tumor. The eradication of the tumor induced by the high dose of L-PAM appeared to be due solely to the tumoricidal effect of the drug. On the other hand, the eradication of the tumor by the low dose of L-PAM also required the participation of antitumor immunity of the host, since subsequent injection of antithymocyte serum abrogated the curative effect of the drug in most mice. Mice cured by a high dose of L-PAM were not resistant to subsequent lethal tumor challenge. In contrast, mice cured by the low dose of L-PAM were able to reject a tumor challenge of 300 times the minimal lethal tumor dose. The results obtained with L-PAM therapy are similar to the results that we had previously reported with cyclophosphamide therapy. Thus, the timing of therapy with a low dose of drug for mice bearing a MOPC-315 tumor is critical for successful therapy. Moreover, the selection of a low dose rather than a high dose of drug to eradicate a large tumor offers the advantage that it results in long-lasting potent antitumor immunity as a consequence of the participation of host antitumor immunity in the eradication of the tumor.

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PubMed1983

The common idiotypic specificity of anti-a2 allotype antibodies: contribution of H and L chains to idiotype expression.

Previously an idiotypic specificity common to anti-a2 allotype Ab from 15 rabbits was detected and characterized. The contribution of H and L chains to the expression of this common idiotypic specificity was determined. Two types of recombinant IgG were prepared: (1) H chains from anti-a2 Ab with L chains from normal a3b4 IgG, and (2) L chains from anti-a2 Ab with H chains from normal a3b4 IgG. By inhibition of binding radioimmunoassay, recombinant IgG having either H or L chains from anti-a2 did not inhibit the binding between anti-a2 Ab and anti-idiotype Ab. By direct binding radioimmunoassay, recombinant IgG of H chains from anti-a2 Ab with L chains from a3b4 IgG reacted with anti-idiotype Ab whereas recombinant IgG with H chains from normal a3b4 IgG and L anti-a2 Ab is determined primarily by the H chain; however, the full expression of the common idiotypic specificity requires the interaction of both H and L chains from anti-a2 Ab.

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PubMed1983

Alpha-macroglobulin-induced release of anti-Ig-coated particles from a subpopulation of rabbit B lymphocytes.

Approximately half of the rosettes formed by rabbit Ig+ lymphocytes (B cells) and anti-coated erythrocytes or glutaraldehyde-fixed bacteria are dissociated upon the addition of rabbit serum. Rabbit serum was fractionated and the rosette-dissociating activity was found in purified preparations of rabbit alpha 1- and alpha 2-macroglobulins. Studies designed to elucidate the mechanism of rosette dissociation suggested that the alpha-macroglobulins dissociated rosettes by causing the release or proteolytic cleavage of the membrane proteins complexed with the anti-Ig-coated particles. These data suggest that the alpha-macroglobulins may have a role in the interaction of B lymphocytes with particulate antigens.

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PubMed1983

Some advantages of curing mice bearing a large subcutaneous MOPC-315 tumor with a low dose rather than a high dose of cyclophosphamide.

Mice bearing a large s.c. MOPC-315 tumor can be cured by a dose of cyclophosphamide (CY) ranging from 15 to 200 mg/kg. However, the low (15 mg/kg) and the high (200 mg/kg) doses mediate tumor eradication via different mechanisms. Tumor eradication by the low dose of drug requires the cooperation of the toxic effect of the drug and T-cell-dependent antitumor immunity. On the other hand, tumor eradication by the high dose of drug does not require the participation of antitumor immunity but depends primarily on the tumoricidal activity of the drug. Spleen cells from tumor-bearing mice treated with the low dose of CY exhibit an augmented antitumor immune potential, whereas spleen cells from tumor-bearing mice treated with the high dose of CY exhibit suppressed antitumor immune potential. More importantly, tumor-bearing mice treated with the low dose of drug are able to reject a challenge with 300 times the minimal lethal tumor dose given 1, 6, or 31 days after CY therapy, whereas mice treated with the high dose of drug are unable to reject such a challenge given within the same time intervals after CY therapy. Moreover, when mice bearing a large tumor are treated with the high dose of CY and subsequently challenged again with tumor cells to establish a Day 4 nonpalpable tumor, this tumor is less responsive to cure by combined chemoimmunotherapy than is a Day 4 nonpalpable tumor established in normal mice. Thus, although the high dose of CY can cure most mice bearing a large-size MOPC-315 tumor, it not only does not result in antitumor immunity, but it actually reduces the effectiveness of chemoimmunotherapy for a second tumor challenge. In contrast, mice cured with the low dose of CY exhibit long-lasting potent antitumor immunity.

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PubMed1982

Rabbit heavy chain haplotypes--allotypic determinants expressed by VH-CH recombinants.

This report summarizes our current understanding of the heavy chain haplotypes found in our laboratories' rabbits. Independently derived data from several laboratories have been synthesizes into a consistent picture of the linked inheritance of allotypic markers found on the different heavy chain classes and subclasses of rabbit immunoglobulins in pedigreed rabbits, including the families of three apparent VH-CH recombinants. In one recombinant, the entire group of CH markers (C mu, C gamma, and C alpha) recombined with the set of VH. Although in the other two recombinants all CH markers may also have recombined as a group, in one of these only IgG and IgA CH genes were informative; in the other recombinant, only the IgG allotypes were informative. Some allotypic determinants found on IgM molecules ("conformational") appear only when a specific variable region allotype (VHa) is combined with a specific mu constant region allotype (C mu). New combinations of VHa and C mu allotypes were generated in two of the genetic recombinants and led to new "conformational" determinants. The gains and losses observed lend support to the hypothesis that the determinants result from conformations generated by the combination of allotype-specific VH and C mu protein sequences. Conceivably, DNA events that join VH to diversity (D)- and joining (J)-coding sequences or mRNA processing events that splice J to C mu could be involved in generating the sequences that form allotype-specific determinants.

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PubMed1982

An increase in the number of recombinant molecules and other effects of the simultaneous allotype suppression of trans-chromosomal a VH and n Cmu Ig gene products.

The concomitant effects of trans-chromosomal allotype suppression of both an a VH and an n Cmu locus allotype in multiheterozygous rabbits were investigated. For example of the expression of the a2 VH and n81 Cmu allotypes were suppressed in a multiheterozygous rabbit having the a1 chi-y-n81de12,15f73g74/a2 chi 32y33n80de12.14f69g77 genotype. This trans-chromosomal allotype suppression led to the concomitant suppression of other CH allotypes in the same parental haplotype as the suppressed-n81 allotype (i.e. the e15, f73 and g74 allotype) and the partial suppression of the a1 VH allotype (from the normal level of 70% of the total Ig to 10%), and also led to compensation by other VH allotypes from the same parental haplotype as the suppressed-a2 allotype (i.e. the x32 and y33 allotypes). The x32 and y33 allotypes were expressed on Ig molecules with the CH allotypes coded by the same haplotype (i.e. the cis molecules). In a further analysis of the IgG molecules having the partially-suppressed-a1 allotype, one-half (5%) of these molecules were trans-chromosomal recombinant molecules (i.e. a1e14 IgG) and the other half (5%) were cis-chromosomal molecules (i.e. a1e15 IgG). The trans-chromosomal a1e14 IgG molecules probably were derived from the expansion of a limited number of lymphoid clones that normally produce only 1.5% trans-chromosomal recombinant molecules. The cis-chromosomal a1e15 IgG molecules were probably derived either from lymphoid clones that survived the suppression by the anti-n81 Ab, or from lymphoid clones that bore a different subclass of IgM (i.e. n-negative IgM).

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PubMed1982

Mode of action of polyethylene glycol 6000 in potentiating the in vitro generation of antitumor cytotoxicity by MOPC-315 tumor bearer spleen cells.

Some of the possible mechanisms by which polyethylene glycol (PEG) augments the ability of MOPC-315 tumor bearer spleen cells to mediate in vitro antitumor cytotoxicity were evaluated. The level of antitumor cytotoxicity obtained in 5-day cultures of tumor bearer spleen cell suspensions correlated inversely with the percentage of Trinitrophenol (TNP)-rosettable cells (presumably metastatic tumor cells) present in the spleen. The kinetics of decrease in the percentage of TNP-rosettable cells coincided with the appearance of antitumor cytotoxicity. In addition, PEG was shown to interfere with the ability of viable tumor cells to suppress the in vitro generation of antitumor cytotoxicity in normal spleen cells cultured with mitomycin C-treated tumor cells. However, the decrease in the content of TNP-rosettable cells and the concurrent increase in the level of antitumor cytotoxicity were not due to direct cytotoxic and/or cytostatic effects of PEG on tumor cells. Spleen cells cultured in the presence of PEG had an increased rate of [3H]thymidine incorporation and proliferation compared to spleen cells cultured in the absence of PEG. However, the PEG-induced decrease in the percentage of TNP-rosettable cells either preceded or occurred at the same time that the PEG-induced increase in spleen cell number was observed. Therefore, spleen cell proliferation can at best explain only partially the PEG-induced decrease in the content of TNP-rosettable cells, and other mechanisms for the decrease must be considered.

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