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Biomedical subjects

A Ahmed

Publications and source records attributed to A Ahmed.

At least 37 records · Page 2Linked to original sources
PubMed1979

Engraftment of bone marrow transplants in W anemic mice measured by electronic determination of the red blood cell size profile.

Defective stem cells of WBB6F1-W/Wv mice produce macrocytic red blood cells (RBCs); stem cells of WBB6F1-+/+ mice produce normocytic RBCs. Utilization of the Coulter counter channelyzer permitted good dissociation between the size distribution of populations of +/+ and W/Wv RBCs. Peaks (mean cell volumes) for +/+ and W/Wv RBCs have been determined to be between the 30th and 40th channel and 50th and 60th channel, respectively. Variability of profiles for individual mice of both genotypes did not exceed the variability of separate determinations of the same cell suspension from a single mouse. Admixture (approximately 15%) of either type of erythrocytes could be quantitatively detected by this method. One week after transplant of 10(7) +/+ marrow cells into W/Wv recipients, 25% of donor type erythrocytes were detected. Eighteen days post-graft, concentration of +/- normocytes exceeded the concentration of macrocytes in the W/Wv recipients' circulation. Approximately 45 days post-transplant, the proportion of macrocytes decreased below the 10% detectable level. Calculation of the daily RBC production rate during repopulation and estimation of the number of RBCs produced by a single hematopoietic colony were determined. The RBC size profile was found to be a convenient method for studying the effect of implantation of W/Wv marrow into lethally irradiated +/+ mice. This method proved suitable for repetitive determination of the size population in individual transplanted mice.

Anemia↗
PubMed1979

Selective production of human antigen specific helper factor from normal volunteers: implications for human Ir genes.

Based on previous systems for generating helper cells and factors from mouse spleen cell cultures, an in vitro system for the production and detection of human helper factors to the synthetic polypeptide antigens (T,G)-A--L and GAT10 was developed. The factors are made by human peripheral blood leucocytes and are antigen-specific, as judged both by functional criteria and specific binding and elution from antigen columns. Out of the first six volunteers studied two were high responders to (T,G)-A--L, but non-responders to GAT, two responders to GAT but not (T,G)-A--L. One subject made factors to both antigens and the sixth reacted to neither. The antigens chosen are known to be under MHC-linked immune response (Ir) gene control in all animal species tested, with some strains being responders while others are not. The selective responsiveness, different between individuals, thus suggests that the response to these antigens in man is under Ir gene control. Because of the small size of the sample initially studied and HLA typed, it was not surprising that there was no clear-cut association of response with any particular histocompatibility type at the HLA-A, B, C or D locus.

Adult↗
PubMed1978

Detection of B cell antibodies in renal transplant recipients.

A retrospective study for the presence of lymphocytotoxic antibodies was performed on sera collected from 119 kidney graft recipients. Sera that had been collected on days 12 to 19 post-transplant were tested for cytotoxic reactions against a panel of human peripheral blood lymphocytes from 60 unrelated donors and 37 to 47 cultured human lymphoid cell lines (LCL). Forty-nine sera were negative against peripheral blood lymphocytes but contained cytotoxic antibody against cells on the LCL panel. Several sera were tested on E rosette-purified peripheral blood lymphocyte B cells and T cells from five donors whose LCL had also been tested. LCL appeared to be more sensitive to cytotoxic reactions than their B cell counterparts and may identify additional specificities which may not be related to the B cell alloantigenic system. Mixed lymphocyte culture blocking experiments were carried out against all combinations of these five cells. Some sera showed reactions of identity for B cells and LCL, and blocked the appropriate stimulator cells in mixed lymphocyte culture. Two sera that were positive for LCL but negative for B cell blocked only responder cells in the mixed lymphocyte culture.

Antibodies↗
PubMed1978

Cellular immunity to cytomegalovirus in a patient following bone marrow transplantation.

Cell-mediated immunity to cytomegalovirus (CMV) was studied in a bone marrow transplant patient with evidence of active CMV infection. The lymphocytes from this patient were found to specifically recognize and respond in vitro by transformation to CMV-infected Wistar-38 fibroblasts and by production of macrophage migration inhibition factor to CMV antigen. In addition, plasma and spinal fluid from the patient were found to contain blocking factor that specifically inhibited the lymphocyte response in the above assays. Biochemical, biophysical, and immunological studies indicate that the blocking factor may be an antigen-antibody complex.

Adolescent↗
PubMed1978

Reactivity of lupus erythematosus antibodies with leukemic helper T cells.

Immunoabsorbent columns, containing membrane fragments of either leukemic "helper" T cells or B cell lymphoblasts, were used to isolate and study antilymphocyte antibodies from plasmas of 2 patients with systemic lupus erythematosus (SLE). Both plasmas contained IgG which bound to and could be eluted from the "helper" T cell column. These antibodies significantly inhibited normal lymphocyte proliferative responses to microbial and histocompatibility antigens. The findings indicate that these SLE plasmas contain immunoglobulins of the IgG class which react with leukemic "helper" T cells and inhibit normal effector T cell function.

Antibodies↗
PubMed1978

Immunoglobulin class distribution of measles virus antibodies in serum and spinal fluids of patients with subacute sclerosing panencephalitis.

Sera and cerebrospinal fluids (CSF) from patients with subacute sclerosing panencephalitis (SSPE) were tested by indirect immunofluorescence for the presence of measles virus specific antibodies of the various heavy chain classes. IgG and IgA antibodies were detected in the CSF while IgG, IgM, IgA, IgD and IgE measles virus antibodies were found in a significant number of the patient sera. Sera from SSPE patients had slightly elevated levels of IgG, IgM, IgD and IgE while IgA was decreased. The heterogeneous heavy chain class distribution of measles antibodies suggests the possibility that non-complement fixing antibodies serve as blocking antibodies which aid in the persistence of intracellular measles virus infection in patients with SSPE.

Antibodies, Viral↗
PubMed1978

In vitro induction of Lyt surface markers on precursor cells incubated with thymosin polypeptides.

Induction of precursor T cells by thymosin fraction 5 was found to generate a population of cells bearing the Lyt 1+, 2+, and 3+ phenotype and functionally capable of providing T-cell helper activity in vitro. However, when the component polypeptides of thymosin fraction 5 were similarly analyzed, several displayed inductive activities quite different from those of the parent preparation. These results suggest that variations in the polypeptide composition determine, to a large part, the inductive properties of a thymosin preparation and that such variations in vivo may serve as a regulatory system for T-cell maturation.

Animals↗