Biomedical subjects

M D Cooper

Publications and source records attributed to M D Cooper.

At least 397 records · Page 22Linked to original sources

PubMed1975

A spectrum of B-cell differentiation defects.

The nonparallel relationships between development of classes of B lymphocytes and of serum immunoglobulins during ontogeny and in some patients imply: 1) that B-cell differentiation is discontinuous and 2) that class-specific-controls for terminal B-lymphocyte differentiation exist. Three separate defects in B-cell differentiation in vivo have been identified using pokeweed mitogen stimulation of lymphocytes. B lymphocytes may fail to develop, may develop but lack the capacity to differentiate further, or may be normal in both respects. The latter result suggests involvement of other cell types in antibody deficiency.

Animals↗

PubMed1975

Development of T and B cells and their functional interactions.

The development of IgM-, IgG- and then IgA-bearing B lymphocytes is an orderly process occurring independently of antigens and T cells. T cells enhance antigen-induced B lymphocyte to plasma cell differentiation according to the hierarchy: IgA greater than IgG greater than IgM. T cells also exhibit antigenindependent and dependent stages of differentiation and a functional diversity, perhaps attributable to different classes of T cells. New evidence indicates the presence of a receptor on T cells for IgM antibody produced by B cells.

Agammaglobulinemia↗

PubMed1975

In vivo effects of cortisone on the B cell line in chickens.

The effects of a single dose of cortisone acetate (5 or 10 mg/100 g body weight) on B cells were examined in young chickens. A dose-dependent increase in numbers of circulating B lymphocytes and a change in their Ig-class distribution were followed by parallel increase in splenic plasma cells and serum immunoglobulins. The higher dose of cortisone produced changes in Bmu and Bgamma cells, whereas the lower dose primarily affected Bmu cells. These steroid-induced changes were preceded by lymphocyte depletion in the cortical regions of bursal follicles, and prior bursectomy prevented steroid-induced increases in circulating B lymphocytes and tissue plasma cells. The results suggest that cortisone can induce bursal lymphocytes to migrate from the bursa and to settle subsequently in peripheral lymphoid tissues where they become mature plasma cells.

Animals↗

PubMed1975

Early lymphoepithelial relationships in human appendix. A combined light- and electron-microscopic study.

The fine structure of human appendix was studied from the earliest stages of lymphoid development in fetuses to the definitive relationships found in children up to 8 years old. Follicular accumulations of lymphocytes were observed first in the mesenchyme immediately beneath epithelium which contained a predominance of goblet cells on the surface and in the crypts. Larger accumulations of lymphoid cells in older fetuses were intimately related to surface epithelium but not to the epithelium of crypts. At the point of invasion of lymphoid cells into surface epithelium, the goblet cell population diminished and epithelial cells displaying a morphologically distinct form of differentiation were observed. They were characterized by the presence of irregular microvilli or microfolds and numerous apical micropinocytotic vesciles. This follicle-associated epithelium (FAE) appeared ultrastructurally identical with epithelium in chicken bursa of Fabricius, mouse Peyer's patch, and rabbit appendix, which has been shown to be capable of transporting ferritin and India ink tracer from the lumen to underlying tissue. It appeared identical to specialized epithelial cells of adult human Peyer's patches. FAE was maintained through the neonatal period into childhood. We speculate that the biological significance of FAE is to provide a channel through which antigens may stimulate clonal proliferation and seeding of B-lymphocytes throughout the lamina propria of internal mucous surfaces.

Appendix↗

PubMed1975

Sequential expression of germ line genes in development of immunoglobulin class diversity.

Differentiation of B cells occurs in two discontinuous stages. Primary differentiation of stem cells to B lymphocytes in birds occurs exclusively in the lymphoepithelial bursa of Fabricius; the fetal liver may serve this function in mammals. In chickens both the size of the B-lymphocyte pool and the generation of precursors for cells secreting different immunoglobulin classes is controlled by the bursa. The latter process involves the sequential expression of genes coding for heavy chain constant regions in the order mu, gamma, alpha. The second stage of B-cell differentiation is antigen-driven, and involves proliferation and maturation of B lymphocytes to plasma cells. Ontogenetic development of different classes of B lymphocytes in mammals is orderly, independent of exogenous antigens, and occurs in the sequence mu, gamma, alpha. A developmental switch in expression of Ch genes, beginning with mu, has been experimentally verified. We favor the hypothesis that generation of class diversity of B lymphocytes occurs during the antigen-independent first stage of differentiation, and that the genetic switch in Ch gene expression follows the sequence mu leads to gamma leads to alpha, but evidence of these points remains inconclusive.

Animals↗

PubMed1975

Serologic studies of Brucella suis and Brucella canis.

Brucella suis strain 3b and Brucella canis strain RM-6-66 were grown on tryptose agar, and aqueous ether extracts were prepared from the cells. The aqueous phase was clarified by centrifugation for a total of 10 hours at 144,700 times g and fractionated with gels and with diethylaminoethyl (DEAE) cellulose. Two fractions from B suis and 1 fraction from B canis were reactive in the indirect hemagglutination test. The sensitizing ability was destroyed by pronase, but was unaffected by ribonuclease or deoxyribonuclease. Apparently, protein or one of its subunits has an important role in antigenic specificity relating to indirect hemagglutination activity. Results in immunoelectrophoretic analysis indicated at least 22 antigens were in the ultracentrifugal supernate (144,700 times g) of B suis and 31 antigens were in a similar supernate of B canis. Results in immunodiffusion and agglutination absorption studies indicated a close relationship existed between B suis and B canis.

Animals↗

PubMed1974