Search PubMed⌕ Search

Biomedical subjects

M D Cooper

Publications and source records attributed to M D Cooper.

At least 379 records · Page 21Linked to original sources
PubMed1976

Ontogeny of B cells in the chicken. I. Sequential development of clonal diversity in the bursa.

The initial development and distribution of lymphocytes expressing surface IgM (sIgM) and of specific antigen-binding cells (ABC) were studied in the chicken in an attempt to gain information on the process by which B-cell diversity is generated. The antigens used were sheep erythrocytes (SE), keyhole limpet hemocyanin (KLH), and poly-L(Tyr, Glu)poly-D,L-Ala-poly-L-Lys (TGAL). The results indicate that generation of the total sIgM-positive population begins in the bursa and that specific clones of ABC develop in a fixed sequential pattern which is not influenced by either deprivation of or deliberate exposure to exogenous antigens. Cells bearing sIgM by immunofluorescence (IgM-positive cells) were detected first in the bursa on the 12th day of incubation, KLH-ABC and TGAL-ABC by the 16th day, and SE-ABC on the 18th day. The doubling time of the sIgM-positive population of bursal cells was determined to be approximately 10 h before significant antigen-independent seeding to the spleen began a few days before hatching. Clonal expansion of SE-ABC in the bursa also appeared to be antigen independent as was the initial development of SE-ABC in the blood and spleen which ceased abruptly after bursectomy at hatching. Specific ABC were observed to develop in multiple bursal follicles as small foci of ABC among the much larger total population of sIgM-positive cells within an individual follicle. Intravenously infused SE-ABC homed to the embryonic spleen but not to the bursa. The results are interpreted as favoring a hypothetical model in which individual stem cells give rise to multiple clones of B cells by a predetermined pattern of sequential expression of variable region genes.

Age Factors↗
PubMed1976

Studies on the generation of B lymphocytes in the mouse embryo.

Using an organ culture technique, the development of B lymphocytes has been studied in a number of isolated embryonic hemopoietic tissues. Developing B lymphocytes were identified by cytoplasmic and surface immunofluorescence using purified class-specific antibodies and a Fab anti-immunoglobulin reagent. In fetal liver cultures these cells were further characterized for Fc and complement receptors and for the presence of mouse-specific B lymphocyte antigen. The results indicate that B lymphocytes develop independently in fetal liver and in fetal spleen; they do not develop in cultures of yolk sac and thymus. In conclusion, it is likely that B lymphocyte maturation in mammals is multifocal and is not dependent upon gastrointestinal influences as suggested previously.

Animals↗
PubMed1976

Tissue distribution of technetium-99m and carbon-14 labeled N-(2,6-dimethylphenylcarbamoylmethyl)iminodiacetic acid.

The synthesis, radiochemical labeling, and tissue distribution characteristics of N-(2,6-dimethylphenylcarbamoylmethyl)iminodiacetic acid are described. The radiopharmaceutical prepared by labeling with 99mTc was rapidly eliminated through the hepato-biliary system of mice. Parent 14C compound was eliminated primarily through the kidney. The 99mTc ion appears to have a greater influence than the organic carrier molecule on the distribution of the radiopharmaceutical.

Animals↗
PubMed1976

A passive hemagglutination test for diagnosis of trench fever due to Rochalimaea quintana.

A passive hemagglutination test devised for diagnosis of trench fever was easily performed and highly sensitive and specific. Tanned sheep erythrocytes were sensitized with soluble antigen from Rochalimaea quintana. The test detected antibody in six of seven cases of primary infection and in four cases of late, relapsed trench fever. Titers of antibody ranged from 1:20 to 1:640. Although both IgM and IgG antibody to R. quintana were detected by passive hemagglutination, IgG appeared to be the major reactive antibody. Antigens involved in the reaction were two types of proteins, one inactivated at 50 C and 60 C and the other at 80 C and 100 C. Of 322 control samples of sera that were tested, only one reacted positively; thus, the test had a specificity of greater than 99%. The single positive reaction was in serum from a patient with Q fever. This finding suggests that, in an area where Q fever is endemic, this disease must be ruled out in the interpretation of a positive passive hemagglutination test. Sera should be tested routinely against tanned, unsensitized erythrocytes, since an occassional sample of serum may agglutinate unsensitized cells. Because of its sensitivity and specificity, as well as its simplicity of performance, the passive hemagglutination test shows promise as a useful procedure for serologic identification of both acute and past infection with R. quintana.

Antibodies, Bacterial↗
PubMed1976

B lymphocyte differentiation induced by lipopolysaccharide. III. Suppression of B cell maturation by anti-mouse immunoglobulin antibodies.

Lipopolysaccharide-(LPS) induced differentiation of mouse B lymphocytes to cells synthesizing large amounts of cytoplasmic IgM and IgG2 could be suppressed by antibodies to mu-chains. Maximal inhibition of LPS-induced differentiation was associated with increased cellular proliferation as measured by incorporation of 3H-thymidine, whereas treatment with anti-mu alone over a wide dosage range did not stimulate cellular proliferation. Spleen cells from newborn mice were suppressed by concentrations of anti-mu several hundred-fold lower than required for adult spleen cells; the adult pattern of susceptibility to suppression was acquired by 1 week of age. No significant differences in susceptibility to anti-mu were found in comparisons of adult spleen, lymph node, bone marrow, and Peyer's patch lymphocytes.

Aging↗
PubMed1976

Cross-reactive T-cell antigens among mammalian species.

Fluoresceinated heteroantisera prepared against T cells of rats, monkeys, and humans were reacted withthymus and spleen cells from 11 selected species. These reagents recognized cross-reacting T cell antigen(s) among rodent species (mouse, rat, guinea pig, and hamster) and among primate species (monkey and humans). With one exception, the cross-reactivity was restricted to a phylogenetic order. All three antisera required relatively few absorptions to achieve T cell specificity for related species when compared to absorption requirements for the isologous species. Differentiation antigens within a phylogenetic order thus appear to be more homologous than other cell surface constituents on T cells.

Absorption↗
PubMed1976

The T cell dependence of B cell differentiation induced by pokeweed mitogen.

The in vitro plasma cell response of human peripheral blood B lymphocytes to PWM was found to be dependent on the presence of T lymphocytes. B lymphocytes cultured alone with PWM did not respond with proliferation or differentiation into plasma cells. When T lymphocytes were added back to B lymphocytes before culture, the number of plasma cells of the IgM, IgG and IgA classes formed increased in proportion to the number of T lymphocytes returned. Allogeneic T lymphocytes from either peripheral blood or adult thymus could effectively substitute for autologous T lymphocytes. By comparing responses of B lymphocytes cultured with equal numbers of autologous or allogeneic T cells, it was found that the considerable variation in the magnitude of the plasma cell response from different normal donors was related to a quality of their T cells; T cells from high responders substantially enhanced plasma cell differentiation of B cells from low responders and vice versa. This T cell "helper function" was irradiation-resistant and was a property of thymocytes as well as peripheral T cells.

B-Lymphocytes↗
PubMed1976

B cell differentiation induced by lipopolysaccharide. IV. Development of immunoglobulin class restriction in precursors of IgG-synthesizing cells.

Direct immunofluorescence was used to determine the classes of immunoglobulins expressed on the surface membrane and in the cytoplasm of newborn and adult B lymphocytes differentiating in response to LPS in vitro. In both newborn and adult spleen, a small proportion of IgM-bearing B lymphocytes also stained for IgG2; adult spleen contained an additional population of lymphocytes bearing IgG2 alone. Combined surface and cytoplasmic staining at intervals after culture initiation and demonstrated both IgM and IgG2 on the membranes of the earliest cells synthesizing cytoplasmic IgG2. At later stages the proportion of IgM-IgG2 surface doubles and of cells synthesizing cytoplasmic IgG2 which had surface IgM fell significantly. Detection of surface IgM on IgG2 precursors correlated with susceptibility of the IgG2 precursors to anti-mu-suppression over the first 3 days in cultures of newborn spleen cells. After 3 days when these cells no longer expressed surface IgM, 2gG2 responses were not suppressed although the IgM response was still inhibited. These results suggest that virgin IgG2 precursors may be B lymphocytes expressing both IgM and IgG2, and that "switching" involves the loss of IgM receptors as these cells proliferate and mature.

Animals↗
PubMed1975

Successful fetal liver transplantation in a child with severe combined immunodeficiency.

Following transplantation with allogeneic fetal liver, a boy with a severe combined immunodeficiency and adenosine-deaminase (A.D.A.) deficiency developed immunocompetent T and B cells in an orderly manner. Engraftment was indicated by appearance of A.D.A. activity and donor-lymphocyte and red-cell antigens. The child remained free of major infections until one year later when he developed an ultimately fatal nephrotic syndrome associated with immune-complex glomerulonephritis.

Adenosine Deaminase↗
PubMed1975

Differences in susceptibility of mature and immature mouse B lymphocytes to anti-immunoglobulin-induced immunoglobulin suppression in vitro. Possible implications for B-cell tolerance to self.

Purified goat antibodies against mouse mu-chains and rabbit antibodies against mouse Ig determinants, and their Fab fragments, inhibited the development of IgM-bearing B cells in explant cultures of 14-day mouse fetal liver, and caused the disappearance of cell surface IgM in explant and dissociated cell cultures of more developed lymphoid tissues. While treatment of cultures of fetal or newborn liver, or adult bone marrow, with low concentrations (less than or equal to 10 mug/ml) of anti-Ig for less than or equal to 24 h caused the complete, but reversible, disappearance (modulation) of cell surface IgM, treatment for greater than or less than 48 h produced irreversible IgM suppression. In contrast, anti-Ig-induced suppression of cell surface IgM in cultures of adult spleen or lymph nodes required much higher concentrations of antibody (greater than or equal to 100 mug/ml) and was always reversible. These differences between immature and mature IgM-bearing cells could not be related to differences in the amount of surface IgM on the cells. The remarkable sensitivity of newly formed B cells to IgM modulation and irreversible IgM suppression when ligands bind to their Ig receptors, may have important implications for B-cell tolerance to self antigens.

Animals↗
PubMed1975

T- and B-cell interactions in autoimmune syndromes.

We have reviewed briefly some of the individual capabilities of T and B cells and how these can be modified by interactions between the two cell lines. Evidence that T cells have their own distinct receptors for antigens, yet under certain circumstances may bind IgM or IgG produced by B cells, has been particularly emphasized. The probability that B cells, in turn, may bind the antigen receptor of T-cell origin reflects the balanced nature of an intricate communication system in which interactions between antigens, antigen receptors, and binding sites for these receptors all serve to modulate the integrated functioning of T and B cells. It is suggested that this communication system is disturbed in patients with rheumatoid arthritis; specifically, it is proposed that defective feedback activity of IgG-antigen complexes on activated T cells may exist in some patients and could result in unchecked and harmful T-cell activity in the joint. Therapeutic implications of this idea are mentioned.

Animals↗
PubMed1975

Early detection of acute rejection in renal allografts using radioiodinated autologous fibrinogen.

131I-labeled autologous fibrinogen was used to detect acute renal allograft rejection in the early postoperative period. Ratios of radioactive counts over transplanted kidneys to those over the heart increased with deposition of radioactive fibrinogen in kidneys undergoing rejection. The test was positive in all instances of acute rejection twelve to twenty-four hours prior to clinical ro biochemical changes. False-positive test results were noted in instances of perinephric hematoma, seroma, and wound abscess and in one patient with urinary tract infection. The test was negative in cases of renal failure secondary to acute tubular necrosis, uric acid nephropathy (in the absence of acute rejection), and chronic rejection. This test is simple, rapid, and practical. It can be performed at the bedside and is free from complications, particularly serum hepatitis.

Acute Disease↗