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Biomedical subjects

M L Misfeldt

Publications and source records attributed to M L Misfeldt.

29 records · Page 2Linked to original sources
PubMed1985

Induction of an immune response in athymic nude mice to thymus-dependent antigens by Pseudomonas aeruginosa exotoxin A.

Exposure of spleen cells from athymic nude mice to Pseudomonas aeruginosa exotoxin A induces these cells to respond to the thymus-dependent (TD) antigen sheep erythrocytes (SRBC). The response induced by toxin is dose dependent, antigen specific, and not due to polyclonal B-cell activation. Enhancement of the anti-SRBC response can be observed when toxin addition precedes antigen stimulation by 24-48 hr, which decreases when toxin administration follows antigen stimulation. A significant response is also observed when toxin and antigen are added simultaneously. A significant anti-SRBC response can be observed out to Day 10 postantigen and toxin stimulation after attaining a peak response at Day 5. Cultures exposed to toxin in the presence or absence of antigen exhibited a higher cell number and relative number of B cells as compared to control cultures. Exposure of T-cell depleted B cells from euthymic +/nu mice to toxin plus antigen does not result in an anti-SRBC response indicating that exotoxin A alone is not sufficient to induce B-cell responsiveness to T-dependent antigens and that other cells and/or factors are involved in the toxin-induced responsiveness of nude mice to T-dependent antigens.

ADP Ribose Transferases↗
PubMed1984

Construction of hybridomas from nude mice with phenotypes of precursors of regulatory T cells. I. A model for study of development of T-cell function in immune systems.

Functional helper and suppressor hybridomas were constructed from fractionated Type II NFR/nude mouse splenocytes which resemble precursors of T cells. After carrier priming with rabbit erythrocytes (RE), splenocytes from Type II NFR/nude mice were fractionated on nylon wool columns. Cells from two distinct fractions (Pool 1 and Pool 2) were fused with BW5147 lymphoma cells. Hybrids were selected in HAT medium and subsequently cloned. Three hybridomas constructed using Pool 1 splenocytes were capable of complementing nude mouse PFC responses to the trinitrophenyl group (TNP) of TNP-RE. Four hybridomas constructed using Pool 2 splenocytes were observed to suppress anti-TNP PFC responses. These hybridomas express the T-cell surface markers TLa, Thy 1, Lyt 1, Lyt 2 in patterns which suggest that they represent expanded clones of T cells from precursors that are arrested in their development. They appear to be blocked short of development of carrier specificity in their functional phenotypes as regulatory T cells.

Animals↗
PubMed1984

Alteration of murine immune response by Pseudomonas aeruginosa exotoxin A.

Pseudomonas exotoxin A has been implicated as a possible virulence factor in Pseudomonas infections. This toxin has a direct cytotoxic effect on a number of cell types, including macrophages and their precursors, and therefore may affect other cells of the immune system. NFR/N(H-2q) (+/nu or nu/nu) mice were immunized with either T-dependent or T-independent antigens along with various doses of exotoxin A. The immune response was then assayed by a modification of the Jerne plaque assay. Exotoxin A induced a dose-dependent suppression of the in vitro and in vivo immune responses to T-dependent and T-independent antigens in immunocompetent +/nu mice. However, in NFR/N nu/nu mice, suppression of the immune response to the T-independent antigen trinitrophenylated-Ficoll was not observed. Instead, a marked enhancement of the response was observed at doses of 100 and 10 ng of exotoxin A. Removal of T-cells with anti-Thy 1.2 antiserum plus complement before antigen and exotoxin A stimulation in +/nu mice results in abrogation of the suppression. These data suggest that Pseudomonas exotoxin A exerts an effect on both B- and T-lymphocyte populations to modulate the immune response and that this activity may be one facet of the pathogenic effects of this toxin.

ADP Ribose Transferases↗
PubMed1981

Complementation of the plaque-forming cell responses of T-cell-deficient nude mice by a T-cell hybridoma.

Spleen cells from NFR/N mice primed with carrier rabbit erythrocytes were passed through nylon wool and fused with cells from the AKR T-cell lymphoma BW5147 in order to construct functional T-cell hybridomas. Several hybrids have been obtained. One of the cloned hybrids possesses a marked capacity to functionally complement the T-cell-dependent hapten-specific plaque-forming cell responses of NFR/N nude mice to the trinitrophenyl group. The hybrids carry the Thy 1 marker of the immune parent, express the Lyt 1 surface marker, possess Fc receptors at their surface, and express an Ig heavy-chain variable region determinant at their surfaces as detected by anti-VH MOPC 315 antiserum.

Animals↗
PubMed1979

Identification of protective cell surface proteins in ribosomal fractions from Salmonella typhimurium.

Cell surface antigen preparations from Salmonella typhimurium SR-11 prepared by either trichloroacetic acid extraction or boiling in sodium dodecyl sulfate were able to protect C3H/HeJ, C3H/HeDub, and A/J mice. Some of the proteins found in these preparations were shown to exist in the protective ribosomal fraction isolated from S. typhimurium SR-11. Passage of ribosomes isolated from S. typhimurium SR-11 and 6707 through a Sepharose 2B column removed the protective immunogen from 6707 ribosomes but did not completely remove it from SR-11 ribosomes. Immunity to salmonella infection in C3H/HeJ mice induced by ribosomal vaccines may be dependent on the presence of cell surface proteins in the ribosomal fraction.

Animals↗
PubMed1978

Protective ability of Salmonella ribosomal protein and RNA in inbred mice.

Ribosomal vaccines prepared from Salmonella typhimurium were effective immunogens in A/J, C3H/HeDub, and C3H/HeJ mice. Purified ribosomal components were also tested as immunogens in the inbred mice. Protein isolated from a Salmonella ribosomal fraction could protect all three mouse strains. Although purified RNA was shown to be protective for A/J and C3H/HeDub mice, it was not protective for C3H/HeJ mice. Protective immunity could be induced in A/J and C3H/HeDub mice by various immunostimulants. Immunity in C3H/HeJ mice, however, could only be induced by Salmonella ribosomes or protein isolated from the Salmonella ribosomal fraction.

Animals↗
PubMed1977

Role of endotoxin contamination in ribiosomal vaccines prepared from Salmonella typhimurium.

Ribosomal vaccines prepared from Salmonella typhimurium SR-11 and 6707 an Re mutant bacterium of strain LT2, were effective immunogens in A/J and C3H/HeDub inbred mice. Only SR-11 ribosomes were able to induce significant protection in C3H/HeJ mice. C57BL/6J mice were not protected by either ribosomal preparation. A/J mice were protected against salmonella infection by purified SR-11 endotoxin preparations. Neither the C3H/HeDub, the C3H/HeJ, nor the C57BL/6J mice were protected by the endotoxin preparation. Passive hemagglutination studies showed that C3H/HeJ mice had no antibodies to O antigen but were significantly protected by SR-11 ribosomes. In contrast, C57BL/6J mice, which had the highest titers of O antibodies of the four inbred mouse strains, were not protected by SR-11 ribosomes. Endotoxin cannot totally account for the effectiveness fo ribosomal account for the effectiveness of ribosomal vaccines prepared from S. typhimurium.

Animals↗
PubMed1976

Variability of protection in inbred mice induced by a ribosomal vaccine prepared from Salmonella typhimurium.

Ribosomal vaccines prepared from Salmonella typhimurium were effective immunogens in A/J inbred mice and C3H/HeTex, inbred mice. However, ribosomal vaccines were not protective in C57BL/6J inbred mice. A/J mice were protected against lethal challenge by attenuated S. typhimurium live-cell, ribosomal, phenol, and heat-killed vaccines. C3H/HeTex mice were protected by live-cell, ribosomal, and phenol vaccines but not the heat-killed vaccine. Only the live-cell vaccine gave significant protection in the C57BL/6J inbred mice. A comparison of the kinetics of infection in sham-immunized mice and mice immunized with ribosomes showed that ribosome preparations elicited protection against Salmonella infection in mice inherently sensitive and resistant to Salmonella.

Animals↗