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Biomedical subjects

A G Bird

Publications and source records attributed to A G Bird.

107 records · Page 6Linked to original sources
PubMed1981

Use of plaque assays to study thyroglobulin autoantibody synthesis by human peripheral blood lymphocytes.

Plaque assays have been used to study thyroglobulin autoantibody synthesis and total immunoglobulin production by cultures of peripheral blood lymphocytes from patients with Hashimoto's thyroiditis. Freshly isolated Hashimoto or normal lymphocytes contained small numbers (7-1300) of total IgG plaque-forming cells (PFC) and total IgM PFC, but specific thyroglobulin antibody PFC was undetectable. After 5-8 days' culture with pokeweek mitogen (PWM), total IgG and IgM PFC were markedly increased to a geometric mean of 10,140 (8414-12,220) IgG PFC and 3450 (163-7534) IgM PFC per 10(6) cultured lymphocytes (95% confidence limits in parentheses). Furthermore, a mean of 63 (22-287) specific IgG thyroglobulin antibody PFC per 10(6) lymphocytes were detectable in cultures of Hashimoto lymphocytes. The IgG thyroglobulin antibody PFC were stimulated by Epstein-Barr virus (EBV) infection, suggesting that EBV infection may be useful in obtaining monoclonal thyroid autoantibodies.

Adult↗
PubMed1981

Polyclonal human T lymphocyte activation results in the secondary functional activation of the human B lymphocyte.

The polyclonal T lymphocyte activators Con A and PHA were demonstrated to induce secretion of IgM and IgG as well as IgA antibodies in cultures of human peripheral blood lymphocytes. A similar response was seen in one-way mixed lymphocyte cultures and the kinetics, dose-response characteristics and optimal culture conditions are presented. The presence of functional T lymphocytes is a prerequisite for in vitro B lymphocyte activation in response to T lymphocyte mitogens. A narrow dose-response profile is a characteristic for both Con A and PHA and polyclonal B cell activation occurred at what have been previously regarded as suboptimal concentrations of these agents. The use of higher doses of these activators failed to generate immunoglobulin-secreting cells despite the presence of early and optimal levels of DNA synthesis in the cultures.

Adult↗
PubMed1980

Mitogenic activation of human lymphocytes: a protein A plaque assay evaluation of polyclonal B-cell activators.

Using the protein A plaque assay, the capacity of various polyclonal B cell activators to induce differentiation in human B lymphocytes was investigated. Dextran sulphate and native dextran were both virtually devoid of mitogenic properties. Lipopolysaccharide, however, was found to be a potent mitogen in human cells that, although giving rise to low DNA synthetic response, induced high numbers of immunoglobulin-synthesizing cells. Mean plaque-forming cell (PFC) numbers in healthy blood donors assayed on the optimal day (days 5-7) were 23,493 IgM/10(6) cells, 11,288 IgG/10(6) cells, and 2643 IgA/10(6) cells. Values obtained in spleen cells, peaking at days 4-6, were slightly higher. Purified protein derivative (PPD) was equally or even more effective than lipopolysaccharide (LPS) in generating PFC of different subclasses in peripheral blood with mean of 29,241 IgM/10(6), 21,269 IgG/10(6), and 3681 IgA/10(6). PPD furthermore induced a marked DNA synthetic response in human lymphocytes. These data suggest that LPS and PPD may both be used as functional markers in human cells when analysing patients with a suspected immunodeficiency state. It is suggested that cultures should be assayed using the protein A plaque assay, thereby being able not only to investigate the individual immunoglobulin classes but also to avoid the possible hazards involved in measuring antigen-specific responses in patients whose prior immunization to the antigen tested can never be totally excluded.

B-Lymphocytes↗
PubMed1980

Nonrandom chromosomal aberrations in chronic lymphocytic leukemia revealed by polyclonal B-cell-mitogen stimulation.

Peripheral blood lymphocytes from 11 patients with chronic lymphocytic leukemia were stimulated by Epstein-Barr virus (EBV), lipopolysaccharide from Escherichia (LPS), and phytohemagglutinin (PHA). Chromosome analysis with the Q-banding technique after 5 days incubation revealed an extra chromosome 12 in 5 of the patients and a translocation between chromosome 11 and chromosome 14 in 1. Two patients had a deletion of chromosome 6, and only 3 patients had a normal karyotype. In most patients, the abnormalities were found in the majority of metaphases after stimulation with EBV, LPS, or both mitogens, while PHA revealed a normal karyotype, with the exception of a total of 4 metaphases in 3 patients. An extra chromosome 12 appears to be specifically associated with chronic lymphocytic leukemia. The frequency of chromosomal abnormalities in this disease appears to be much higher than has previously been thought.

B-Lymphocytes↗
PubMed1979

Lipopolysaccharide and lipid A-induced human blood lymphocyte activation as detected by a protein A plaque assay.

Various purified cell wall lipopolysaccharides (LPS) from gram-negative bacteria and derivatives of these LPS were tested for their stimulatory capacity for human peripheral blood cells. Immunoglobulin (Ig) production was tested by an indirect plaque-forming cell assay using Staphylococcus aureus protein A-coupled erythrocytes and specific anti-Ig as developing serum. This method allows the detection of the majority of cells secreting Ig of a single class, and the number of plaque-forming cells detected are approximately 100-1000 times the amount obtained using normal sheep red cells as targets. LPS containing the O antigen-specific chain, as well as mutant products only containing lipid A and ketodeoxyoctonate trisaccharide, could induce cell division and antibody synthesis. The polypeptide antibiotic polymyxin B was found to inhibit LPS-induced activation. Furthermore, purified lipid A, complexed with bovine serum albumin, was also found to activate human peripheral blood B cells. These findings demonstrate that human peripheral blood lymphocytes can be activated by LPS and also indicate that lipid A is the active part of these molecules.

DNA↗
PubMed1979

Mitogen-induced differentiation of human CLL lymphocytes to antibody-secreting cells.

Peripheral blood lymphocytes from nine patients with chronic lymphatic leukaemia (CLL) have been stimulated by photohaemagglutinin, pokeweed mitogen and Epstein-Barr virus. Our results provide proof that the leukaemic B cells in CLL are capable of responding to mitogenic signals by producing and secreting antibodies, transforming into blast cells, and, probably, increasing their rate of DNA synthesis.

Antibody Specificity↗
PubMed1979

A live human B-cell activator operating in isolation of other cellular influences.

Using a reversed haemolytic plaque assay, we demonstrate that live but not inactivated Epstein-Barr (EB) virus can induce human blood lymphocytes to polyclonal Ig (IgM and IgG) secretion in vitro. Unlike pokeweed mitogen this B-cell-activating effect takes place in relative absence of T cells. EB virus thus promises to be a tool for study of B cell function isolated from other cellular influences, although its mechanism of activation appears to be different from that of previously known B cell activators.

Adult↗
PubMed1979

Pokeweed mitogen induced differentiation of human B cells: evaluation by a protein A haemolytic plaque assay.

Using the protein A plaque assay, the number of human cells secreting immunoglobulin of various classes after pokeweed mitogen stimulation was determined. At optimal response (on day 5-7) a mean of 58,354 IgM PFC/10(6), 34,207 IgG PFC/10(6) and 10,525 IgA PFC/10(6) cells was found when using peripheral blood lymphocytes. In spleen cells, peak values which were slightly higher than in blood, were obtained at day 4-6. The proportions of cells secreting light chains of either type were found to be comparable to those of unstimulated cells thus supporting the notion of the polyclonality of the response. Pokeweed mitogen stimulation of peripheral blood lymphocytes was found to be totally T-cell dependent whereas the response of spleen cells was not. When assayed for antigen-specific precursor cells in cultures stimulated by mitogen, the frequency of SRBC-specific IgM producing cells was found to be 1.3/1000 cells. This frequency was regularly found to be independent of medium supplement.

Antibody-Producing Cells↗
PubMed1978

Appearance of killer (K) cells in the mesenteric lymph nodes in Crohn's disease.

The local lymph node in Crohn's disease contains killer (K) cells which are able to lyse antibody-coated heterologous target cells. K cells are not found in mesenteric lymph nodes from control patients not suffering from Crohn's disease, whereas they are regularly found in similar amounts in the peripheral blood of both control and patients with Crohn's disease. Even mesenteric lymph node cells from areas not macroscopically affected by inflammatory disease show increased K cell activity as compared to control lymph node lymphocytes, suggesting a generalized mesenteric lymph node involvement with regard to K activity in Crohn's disease.

Adult↗
PubMedDate not supplied

B cell differentiation and lymphocyte surface phenotype in late onset hypogammaglobulinaemia.

Lymphocyte function and cell surface phenotype were examined in fifteen patients with late onset hypogammaglobulinaemia. The percentage of surface immunoglobulin-positive B cells in fourteen of the fifteen patients was in the normal range. Patients' B cells expressed MHC class II antigens at normal levels. For one patient, there was relatively high sIgD and low sIgM expression on B cells; the rest of the patients did not differ from controls in surface immunoglobulin density. The proportion of B cells positive for CD5 in patients was comparable to normal controls, and considerably less than in cord blood. However, the pattern of immunoglobulin isotype secretion in vitro by patients' B cells closely paralleled responses of cord blood B cells. Spontaneous secretion of IgM and IgG by patients' B cells was very low. Following polyclonal activation in the presence of autologous T cells, cells from thirteen patients secreted IgM within the normal range in response to at least one activator. The response of patients' purified B cells to IL-2 and gamma-IFN was variable. For four of six tested, B cells cultured with IL-2 and gamma-IFN together with polyclonal activators secreted normal levels of IgM. B cells from the other two patients secreted little or no IgM in response to these cytokines. For fourteen patients, IgG secretion following polyclonal activation remained low both when B cells were cultured with T cells or with a combination of IL-2 and gamma-IFN. IgG subclass imbalance was seen in one patient, whose cells secreted an unusually high proportion of IgG3, and undetectable IgG2 and IgG4; this pattern was consistent whether T cell help was provided by autologous or allogeneic T cells. Similarly purified B cells from this patient showed deficient IgG2 and IgG4 production in response to IL-2 and gamma-IFN.

Adult↗