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Biomedical subjects

N H Collins

Publications and source records attributed to N H Collins.

32 records · Page 2Linked to original sources
PubMed1988

Tolerance of engrafted donor T cells following bone marrow transplantation for severe combined immunodeficiency.

Patients transplanted for the treatment of severe combined immunodeficiency (SCID) frequently develop a unique state of split lymphoid chimerism. Such patients have T cells of donor origin, and non-T cells which are predominantly or exclusively of host origin. We have studied the reactivity of engrafted donor T cells to host and/or donor antigens in 12 patients transplanted for SCID, focusing on the characteristics of the tolerance to host and/or donor MHC antigens observed in nine of these patients who were recipients of T-cell-depleted, haploidentical parental bone marrow. In both proliferative and cytolytic assays, engrafted, donor-derived T cells were shown to be selectively nonreactive to histoincompatible host cells. This tolerance could not be ascribed to cells with suppressive activity in the engrafted T-cell population. T cells from a subset of patients, however, exhibited proliferative but not cytolytic reactivity to donor peripheral blood mononuclear cells. The responding cells were shown to be donor-derived CD3+ cells and were predominantly reactive to B-cell fractions from the donor. Two patients who received transplants from each parent in sequence engrafted T cells from one parent and had non-T cells of host, paternal, and maternal origin. The engrafted T cells proliferated weakly to B cells from the other parent, but were tolerant in cytolytic assays. Donor anti-donor reactivity was seen only in haploidentical split chimeras who had not been treated with cytotoxic drugs prior to T-cell engraftment. This proliferative reactivity toward donor may be due to an absence of donor derived Ia+ antigen presenting cells resident in the thymus of SCID patients at the time when the T-cell repertoire is being shaped.

B-Lymphocytes↗
PubMed1986

Clonable T lymphocytes in T cell-depleted bone marrow transplants correlate with development of graft-v-host disease.

Early clinical trials using T lymphocyte-depleted human marrow for transplantation have reported that such grafts reduce, to varying degrees, both the incidence and the severity of graft-v-host disease (GVHD). However, to date, no clear estimates have been made as to what degree of T cell depletion is necessary to prevent GVHD in every case. To address this problem, we used a limiting dilution assay (LDA) to quantitate residual clonable T lymphocytes in human T cell-depleted bone marrow in 31 HLA-identical transplants for leukemia. The number of phytohemagglutinin -interleukin 2-responsive T lymphocytes determined by LDA and expressed as T cell per kilogram recipient weight was found to correlate with the subsequent development of GVHD: no patients who received less than 1 X 10(5) T cell per kilogram developed GVHD (N = 24). Of the seven patients who received 1 X 10(5) to 4.4 X 10(5) T cell per kilogram, four patients developed grade I or II skin GVHD. This study thus provides a quantitative estimate of the number of T lymphocytes necessary to initiate clinically detectable GVHD in an HLA-identical host.

Bone Marrow↗
PubMed1985

Quantitation of T lymphocytes in human bone marrow by a limiting dilution assay.

A limiting-dilution microculture assay (LDMA) for quantitation of T lymphocytes in human bone marrow is described. Phytohemagglutinin (PHA)-responsive T cells are maintained in interleukin 2 (IL-2)-containing medium with feeder cells in a total volume of 20 microliter. After 16 days of culture, each well is scored by microscopic examination as positive or negative based on the presence or absence of cell growth. A limiting dilution analysis of the relationship between the number of cells seeded per well and the fraction of wells without growth demonstrate that the data are consistent with single-hit kinetics. Minimum chi square statistics were used to establish the line of best fit to calculate the T lymphocyte frequency in a sample. This method for enumeration of T cells was applied to untreated samples of bone marrow, soybean-agglutinin-negative (SBA-) marrow, and soybean-agglutinin-negative marrow cells subjected to a single sheep red blood cell (SRBC) rosette (SBA-E-) or double SRBC rosette (SBA-E-E-) depletion. It was demonstrated that the LDMA can detect as few as 4.3 X 10(5) T cells in a total of 10(9) bone marrow mononuclear cells. The assay system also allows for a comparison of T lymphocytes in the untreated marrow with the T-cell-depleted marrow samples. The mean number of T cells in untreated marrow was 1 X 10(9) and in T-cell-depleted samples 4.3 X 10(5). This corresponds to a 3.5 log or 99.96% reduction in total T cell number by the SBA-E-rosette technique. The phenotypic analysis of single positive wells as well as pooled cells from all positive wells indicate that at least 95% of the wells scored microscopically as positive for T cell growth did in fact contain T cells. The assay requires only 1 X 10(6) mononuclear cells for complete analysis and, therefore, compares favorably with previously published methods.

Bone Marrow Cells↗
PubMed1984

Comparison of one-dimensional IEF patterns for serologically detectable HLA-A and B allotypes.

A new mouse monoclonal antibody (MoAb) 4E, which detects an epitope shared by HLA-B locus antigens, together with the MoAb W6/32, detecting a common HLA, B, C, determinant, and the MoAb4B, detecting HLA-A2 and A28, were used to isolate HLA-A and -B antigens in sequential immunoprecipitation. The HLA antigens obtained from metabolically labeled cell extracts of B-lymphoblastoid cell lines or from phytohemagglutinin (PHA)-activated peripheral blood lymphocytes were compared by one-dimensional isoelectric focusing (1D-IEF). The IEF banding patterns obtained with native HLA antigens segregated in a family with HLA. Neuraminidase treatment of isolated antigens reduced the number of bands to one or two, simplifying the analysis of characteristic patterns. Thus, we have cataloged IEF banding patterns for the majority of the serologically recognized HLA-A and -B allotypes obtained from 57 unrelated American Caucasians. While no HLA-A locus or HLA-B locus specific banding patterns were observed, the HLA-A antigens had, in general, slightly higher pI values than the HLA-B antigens. HLA-C antigens could not be detected in this assay system. The polymorphism detected by IEF banding patterns was as extensive as the serologically detected polymorphism identified by classical HLA serology. Moreover, variants for some HLA allotypes could be detected by this method. In addition to previously recognized A2 variants, new variants were identified for HLA-A1, A26, and Bw44. Each A1 and Bw44 variant was associated with particular haplotypes. The HLA-A2 antigens occurred on 43 HLA haplotypes in the unrelated Caucasian population. Only one of each A2 variants was identified in this population.

Alleles↗
PubMed1983

Influence of size and gene dosage on the survival of skin allografts on rats rendered tolerant at birth.

The attributes of the test grafts with which putatively tolerant rats are challenged influence their immune response. Lewis (Lew) rats inoculated at birth with Lew/BN F1 hybrid bone marrow cells accept large skin allografts more readily than small allografts, and F1 hybrid skin grafts survive better than BN transplants. The results indicate that the survivals of these major histocompatibility complex-incompatible grafts are determined by the same factors that operate when only weak histoincompatibilities prevail.

Animals↗
PubMed1982

Functionally different T lymphocyte subpopulations determined by their sensitivity to complement-dependent cell lysis with the monoclonal antibody 4A.

A human T lymphocyte antigen 4A (40,000 daltons) is defined by a monoclonal, complement- (C) fixing, hybridoma-produced antibody (moAb 4A). This antigen, which is identical to the previously reported antigen 3A 1, is expressed at quantitatively different levels on functional subsets of peripheral T lymphocytes as determined by the cell sensitivity to antibody and C. Peripheral T lymphocytes can be divided into two populations: 4A high-density T cells (4A increases), which are killed in vitro by moAb 4A + C, and 4A low-density T cells (4A decreases), which are not affected in vitro by moAb 4A + C treatment. The helper/inducer T cell lineage, defined by moAb Leu 3a, and the cytotoxic/suppressor T cell lineage, defined by moAb Leu 2A, contain both 4A increases and 4A decreases T cell populations. Functional studies by moAb 4A + C treatment show that 1) the 4A increases T cell population contains T helper cells, which are necessary for in vitro antibody production against red cell-bound determinant; 2) the 4A decreases T cell population contains the precursor T cells, which proliferate in vitro in MLC, and the precursor T cells, which are necessary for the in vitro generation of the alloreactive cytotoxic T cells; and 3) the cytotoxic activity of alloreactive T cells generated in CML assay is abrogated by moAb 4A + C treatment; 4) the activation of T cells by PHA and Con A increases the quantitative expression of 4A antigen.

Antibodies, Monoclonal↗
PubMed1979

The behavior of H-Y-incompatible neonatal skin grafts in rats.

It has been well documented that virgin female rats previously systemically sensitized against H-Y antigen almost invariably reject male skin isografts of adult origin. However, when the donor is a neonatal animal, these H-Y-incompatible grafts are often permanently accepted. Furthermore, such neonatal male skin grafts are frequently able to induce a state of unresponsiveness to subsequent grafts of adult male skin. This ability to induce tolerance is evidently dependent upon the persistence of the neonatal skin graft as it does not occur if the neonatal graft is rejected. Thus, the behavior of H-Y-incompatible neonatal skin grafts in rats parallels their behavior in mice.

Animals↗