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Biomedical subjects

T A Potter

Publications and source records attributed to T A Potter.

At least 55 records · Page 3Linked to original sources
PubMed1985

Genetic control of natural resistance to Trypanosoma rhodesiense: transfer of resistance with bone marrow or spleen cells.

Inbred strains of mice differ greatly in their innate resistance to Trypanosoma rhodesiense, the etiologic agent of African sleeping sickness. BALB/c mice are very susceptible to this organism, whereas C57BL/6 mice are highly resistant. This difference is regulated by at least three distinct genes. An adoptive transfer study was performed in order to determine the tissue site of expression of these genes. Three inbred mouse strains (C57BL/6J, C3H.SW/SnJ, and BALB.B) that differ in resistance to T. rhodesiense, but are histocompatible at the H-2 locus, were used in the study. The adoptive transfer of normal bone marrow cells from C57BL/6J (resistant) mice into X-irradiated BALB.B (susceptible) mice rendered the recipient mice resistant to a subsequent experimental challenge with T. rhodesiense. Conversely, the transfer of bone marrow cells from BALB.B mice into irradiated C57BL/6J mice rendered the latter mice susceptible. Resistance could also be adoptively transferred from C57BL/6J mice to a second susceptible strain, C3H.SW/SnJ, by using either bone marrow or spleen cells. These findings demonstrate that although multiple genes control innate resistance to T. rhodesiense, all or most of these genes appear to control the development or function of cells whose progenitors reside in the spleen and bone marrow.

Animals↗
PubMed1984

Expression of H-2Db on the cell surface in the absence of detectable beta 2 microglobulin.

In this report we describe a variant of the C57BL/6 T lymphoma EL4 (EL4/Mar) which, in contrast to the parental cell line, expresses neither H-2Kb nor beta2-microglobulin (beta2m) but which does express H-2Db detectable by serology and by alloreactive cytotoxic T lymphocytes (CTL). This observation raises the possibility that H-2Db and perhaps other major histocompatibility complex class I molecules are normally not associated with beta2m on the cell surface. In addition, this report is the first to indicated that alloreactive CTL can interact with a beta2m-free class I antigen.

Animals↗
PubMed1984

CTL recognize different determinants from those defined serologically on Ld somatic cell mutants.

Reciprocal Ld structural mutants have been isolated from a somatic cell line. Testing of allogeneic CTL clones on these mutants suggests that the majority of CTL clones recognize determinants different from those that elicit antibody production. Of 36 CTL clones tested, only three clones appeared to recognize a determinant that was related to the negatively selected serologic determinant. However, mAb blocking studies suggest that inhibition of CTL activity by anti-H-2 mAb does not necessarily reflect the fine specificity of the CTL activity.

Animals↗
PubMed1983

Epitopes on H-2Dd somatic cell mutants recognized by cytotoxic T cells.

We have generated several cell lines that express an altered H-2Dd molecule. These cell lines, which were selected for by the failure to express the serological specificity reacting with the monoclonal antibody 34-2-12, have also undergone alterations in epitopes recognized by CTL. One of the mutants, 2.12(-4) was not killed by an allogeneic anti-Dd CTL line, CTLL-A2, even though this line was cytotoxic for the parental cell line and two other 34-2-12- mutant lines. Two of the 34-2-12- mutant lines had an identical serological profile using other monoclonal Dd antibodies, however these two mutants differed markedly in their susceptibility to cytotoxicity by CTLL-A2. In addition to the determinants recognized by allogeneic CTL we also examined the effect of the mutation on the determinants involved in restricting the anti-FITC modified-self-cytotoxic response. An anti-FITC-Dd CTL line did not react with two of the mutants and reacted only weakly with the other mutant, demonstrating not only that the Dd epitopes recognized by this cell line and the allogeneic CTL were different, but also that it is possible for a H-2 class I molecule to express epitopes recognized by allogeneic CTL but not epitopes that function as restricting elements to certain antigens. The observation that both T cell- and B cell-defined determinants were altered in these mutant cell lines is in contrast to the findings, with the mutant mouse strains which were selected for by changes in T cell-defined determinants, which show few, if any, alterations to serological specificities. Characterization of T cell-recognized epitopes expressed on serologically selected somatic cell variants may therefore prove to be most useful for the study of structure-function relationships of H-2 class I molecules.

Animals↗
PubMed1983

H-2 hemizygous mutants from a heterozygous cell line: role of mitotic recombination.

Variants that no longer express an entire H-2 haplotype were readily isolated, by immunoselection with antisera directed against the haplotype, from an H-2b/H-2d heterozygous Friend leukemia cell line carrying a Robertsonian translocation of the chromosomes bearing the H-2 genetic region. These variants can be denoted as being of the phenotype H-2b- H-2d+ or H-2b+ H-2d-. Some of the H-2b- H-2d+ variants: (1) lack the restriction enzyme fragments characteristic of the missing H-2b haplotype, as assessed by Southern blot analysis; (2) express more cell surface H-2d antigens than wild-type cells, as assessed by flow microfluorimetry; and (3) appear to have become homozygous for the more active H-2d-linked allele at the Glyoxalase I locus. These variants thus seem to have lost genetic material corresponding to the H-2b haplotype and may have gained genetic material corresponding to the H-2d haplotype. These results are consistent with the possibility that these variants were generated by mitotic recombination.

Animals↗
PubMed1981

Identification of new murine lymphocyte alloantigens: antisera prepared between C57L, 129 and related strains define new loci.

Antisera prepared by immunizing between the strains 129 and C57L and other related strains identified new antigens expressed on lymphocytes and in particular on thymocytes. Absorption analysis demonstrated that the antisera were complex, and contained several new antibodies including some which were not cytotoxic, but could be detected by rosetting. The loci defined by these antibodies are referred to as Ly-9, Ly-11, Ly-12, Ly-13, and Ly-14, although several of the antigens were not confined to lymphocytes. In addition, the Ea-7 specificities, previously considered to be purely red-cell alloantigens, were also found on thymocytes.

Absorption↗
PubMed1981

Ly-15: a new murine lymphocyte alloantigenic locus.

Immunization between CXB recombinant inbred mice selected for their identity at known loci led to the production of antisera recognizing two specificities: the previously described Ly-9.2 alloantigen and a new specificity, Ly-15.1. A monoclonal antibody to the Ly-15.2 specificity is also described. The Ly-15 specificities were found on thymus, on lymph node and spleen cells, and on liver, but were absent from kidney, brain, and red blood cells.

Animals↗
PubMed1981

Flow microfluorometric analysis of H-2L expression.

The cell surface expression of H-2L, a major transplantation antigen, was compared by flow microfluorometry to the expression of products of H-2K and H-2D loci, using monoclonal antibodies. By this methodology, the ontogeny and tissue distribution of Ld antigens were found to be indistinguishable from those of the K and D antigens. In a reciprocal blocking assay, using fluorescein-labeled test reagents, it was shown that monoclonals anti-H-2.65 and anti-H-2.64 did not inhibit the binding of each other. These results suggest that the alloantigenic determinants H-2.64 and H-2.65 are located at distinct sites on Ld molecules. Quantitative comparisons using the fluorescein-labeled monoclonal reagents indicated that Ld molecules are expressed at 2- to 3-fold lower levels on the cell surface compared with K and D molecules. These findings give new credence to a "3-locus" model for the major histocompatibility complex of man and mouse, where H-2L and HLA-C share several homologies that are unique and distinguish them from the other histocompatibility loci.

Animals↗
PubMed1980

Flow microfluorometric analysis of alloantigen expression during T cell development.

The fluorescence-activated cell sorter (FACS) was used to examine the expression of several alloantigens on T cells: Thy-1, Lyt-1.1, Lyt-2.1, Ly-5, Ly-6 and Ly-7. Antibodies secreted by monoclonal cell lines were used to characterize the Thy-1:2, Lyt-1.1 and Lyt-2.1 antigenic determinants, whereas Ly-5.1, Ly-6.2 and Ly-7.2 determinants were identified with alloantisera raised by conventional hyperimmunization. Using indirect immunofluorescence with fluorescein isothiocyanate-conjugated reagents, the profiles obtained with the FACS demonstrated that: (a) the expression of Thy-1 is greater on normal thymocytes than on cortisone-resistant thymocytes (CRT), lymph node and spleen cells; (b) in contrast to Thy-1, the expression of Ly-1 on normal thymocytes is less than on CRT, lymph node and spleen cells; (c) about 90% of normal thymocytes abut less than 50% of CRT, spleen and lympho node T cells are Lyt-2+ and (d) although weakly expressed on normal thymocytes, the amount of Ly-6 and Ly-7 present on peripheral T cells was considerably increased. The significance of these findings and the potential for further analysis of T cell developmental pathways is discussed.

Animals↗
PubMed1980

Murine lymphocyte alloantigens. I. The Ly-6 locus.

The Ly-6 locus and the Ly-6.2 specificity have been previously described, and we now further define this locus and the allelic specificities, Ly-6.1 and Ly-6.2. Back-cross studies and examination of several recombinant inbred (RI) lines demonstrate that Ly-6 is distinct from other loci determining CMAD, except for ALA-1 and evidence is presented for the identity of Ly-6 and ALA-1. The Ly-6 congenic strain C3H.B6-Ly-6b is described and was used to prepare antisera in combinations congenic for Ly-6. The allelism of the Ly-6.1 and Ly-6.2 specificities was confirmed by the reactivity of these antisera with a segregating F2 generation. Antisera can be prepared between the Ly-6 congenic strains, although the magnitude of the response is under the control of one or more genes in A strain, not linked to H-2 or Ly-4 loci. Absorption analysis using separated T and B lymphocyte populations demonstrate that Ly-6.2 does not have exclusive peripheral T cell representation as originally reported, but is also present on B cells in amounts one-fourth to one-eighth of that found on T cells and is found in greater quantities on T blast cells.

Alleles↗
PubMed1980

The surface phenotype of a suppressor cell of delayed-type hypersensitivity in the mouse.

Delayed-type hypersensitivity (DTH) to horse red blood cells was induced in cyclophosphamide-treated CBA/H mice. The DTH reaction, represented by an increase (0 x 8--1 x 0 mm) in footpad thickness 24 h after secondary challenge, could be suppressed by the adoptive transfer of 10(7) splenic lymphocytes from syngeneic mice primed with 10(9) HRBC. The surface antigenic phenotype of the suppressor cell was determined by the formation of EA, EAC, or Ig rosettes followed by depleting the rosetted populations on Isopaque-Ficoll. The suppressor cell was found to be Ig-, FcR- and CR-, although some suppression was observed with FcR+ cells. Cell depletions with cytotoxic alloantisera and rabbit complement further characterized the suppressor cell as being Thy-1+, Ly-1+, 2-, 3-, 4-, 5+, 6+, 7-, Ia- and IJ-. This cell surface phenotype if unique and differs from the Ly-1-, 2+, 3+, I-J+ suppressor cell of antibody formation and from the recently described Ly-+, 2+, 3+ feedback suppressor T cell.

Animals↗
PubMed1980

Murine lymphocyte alloantigens. II. The Ly-7 locus.

The murine Ly-7 locus was identified by the reactivity of alloantisera prepared as B6,C-H-2d x CXBG)F1 anti-CXBK. Most strains, except C57BL/6 and related strains, were Ly-7.2+. Absorption analysis demonstrated that the Ly-7 specificity was only found on lymphocytes and was absent from liver, kidney, brain, and red blood cells. Direct testing by cytotoxicity and protein A rosetting showed that Ly-7 is expressed in very low amounts on thymocytes, but is readily detectable on more mature T and B lymphocytes (including antibody-forming cells), with the greatest expression on B cells. Typing backcross mice with Ly-7.2 Ly-4.2, H-2.33 antisera showed that Ly-7 is not linked to the Ly-4 or H-2 loci. In raising the antisera by hyperimmunization, it was found that the antibody response to the Ly-7.2 specificity was influenced by an H-2-linked immune response gene.

Animals↗
PubMed1980

Monoclonal antibodies to murine cell surface antigens. I. Lyt-1.1.

The production and properties of a monoclonal anti-Lyt-1.1 antibody are described. The monoclonal antibody is of the IgG2a subclass, is cytotoxic, and reacts with Staphylococcal protein A. The tissue culture supernatant has the same activity (titer on thymus > 1/1000) as an anti-Lyt-1.1 produced by a standard immunization procedure, and after in vivo passage of the hybridoma cell line, the serum titer was > 1:10(6). The monoclonal antibody has the same strain and tissue distribution as the conventional antibody, including reactions on Lyt-1 congenic strains, and it precipitates a cell surface molecule of m.w. approximately 67,000. In nonprimed mice, there were similar numbers of Thy-1+ and Lyt-1+ cells in spleen, lymph node, and thymus. By using the monoclonal reagent, T-helper and T-killer cells in an allogenic system were shown to be Lyt-1.1.

Animals↗
PubMed1978

Detection of mouse alloantibodies by rosetting with protein A-coated sheep red blood cells.

Staphylococcal protein A has an affinity for the Fc portion of the IgG molecule of different species and can therefore be used to detect cell-bound immunoglobulin. Using this property, protein A coupled to sheep red blood cells via chromic chloride can detect alloantibodies to mouse H-2, Thy-1, Ly-1, 2, 4, 5, 6, and 7, and Ia antigenic specificities bound to the surface of lymphocytes by the formation of rosettes. In comparison with other rosetting and cytotoxicity assays, the protein A assay shows a greater sensitivity than does cytotoxicity using spleen cells as the target, as does the sheep anti-mouse Ig rosetting assay, whereas cytotoxicity shows greater sensitivity with some antisera on thymocytes. The major advantages of the protein A assay are that constant low reproducible backgrounds are obtained, there is no need to remove surface Ig by capping prior to antiserum treatment, and that viable cells can be recovered.

Animals↗