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Biomedical subjects

R A Good

Publications and source records attributed to R A Good.

At least 901 records · Page 50Linked to original sources
PubMed1972

Ontogeny of bursal function in chicken. 3. Immunocompletent cell for humoral immunity.

To study the occurrence of immunocompetent cells directly responsible for antibody production, cells from yolk sac, embryonic liver, bursa of Fabricius, bone marrow, spleen, or thymus were injected together with SRBC and Brucella abortus into 4-day old cyclophosphamide-treated chicks. A second stimulation was given 4 days later, and samples taken 4 days thereafter were used for antibody titrations. During ontogeny, immunocompetent cells appeared in significant numbers first in the spleen for anti-SRBC responses, but in the bursa for anti-Brucella responses. Later these cells were also found in thymus and bone marrow. In the bursa, cells immunocompetent for anti-SRBC response were not encountered in significant numbers. The slight response to SRBC by transferred bursa cells reflects the presence of stem cells and their immediate descendents in the bursa at different stages of development. These findings are compared with the development and maturation of the stem cell responsible for humoral immunity. In the bursa, development of the stem cell population precedes that of immunocompetent cells. The opposite relationship was found in bone marrow, spleen, and thymus where immunocompetent cells were always present some weeks before the appearance of cells capable of achieving a long-lasting reconstitution of bursa-dependent functions. These observations reveal that the bursa seeds out immunocompetent cells during its entire postembryonic development, but does not release the lymphoid stem cell population before this population has matured sufficiently and before the bursa itself, after fulfilling its function, starts to involute.

Animals↗
PubMed1972

Mechanism of action of migration inhibitory factor (MIF). I. Evidence for a receptor for MIF present on the peritoneal macrophage but not on the alveolar macrophage.

The initial interaction between migration inhibitory factor (MIF) and the guinea pig alveolar and peritoneal macrophage was studied. MIF-containing supernatants were generated from sensitized lymph node lymphocytes obtained from guinea pigs immunized with bovine gamma globulin in complete Freund's adjuvant. MIF-containing supernatants were markedly inhibitory for the migration of the peritoneal macrophage but had no effect on the alveolar macrophage. A linear relationship was observed between per cent inhibition of migration and serial twofold dilution of supernatant. Reexpressed in arbitrary MIF units, this relationship reflects a dose-response relationship with saturation characteristics. Pulse exposure of peritoneal macrophages to MIF resulted in adsorption of MIF onto both viable and nonviable cells with corresponding depletion of supernatant MIF. The alveolar macrophage did not adsorb MIF. Pulse adsorption of MIF onto the peritoneal macrophage is dependent on time, temperature, and cell number. Pretreatment of the cells with proteolytic enzyme prevents the adsorption of MIF while leaving migration unaffected. These observations support the existence of a specific cell surface receptor for MIF. The existence of such a receptor provides selectivity of immune modulation of macrophage populations by lymphocytes in delayed hypersensitivity reactions.

Animals↗
PubMed1972

Development of chicken lymphoid system. II. Synthesis of primordial immunoglobulin M by the bursa cells of chick embryo.

Development of Ig-synthesizing cells in the bursa of chick embryo was studied by immunohistochemical staining method as well as by in vitro incorporation of leucine-(3)H into Ig. Ig-synthesizing cells are first detected in the bursa of a 14 day old chick embryo and increase with the maturation of the embryo. Acrylamide gel analysis of leucine-(3)H-labeled Ig shows that synthesis of nonsecretory IgM-H(0) precedes that of secretory IgM-H, reflecting an ontogenetic sequence of development of lymphoid cells synthesizing IgM. Since IgM-H(0) is not secreted, we further studied biochemical differences between two heavy chains. The difference is attributable to lack of galactose attachment to H(0) chains. It is proposed that during differentiation of lymphoid cells synthesizing and secreting Ig, attachment of galactose may play an obligatory role in the development of cellular capacity for Ig secretion.

Acrylamides↗
PubMed1972

Development of chicken lymphoid system. I. Synthesis and secretion of immunoglobulins by chicken lymphoid cells.

Synthesis and secretion of Ig by chicken lymphoid cells was studied. Both spleen and bursa cells synthesize and secrete IgM and IgG whereas Ig was not detected in thymus cells. In contrast to the spleen cells which synthesize H and L chains in balanced quantities, the bursa cells synthesize and secrete free L chains. In addition to the lymphoid cells which secrete IgM or IgG, the bursa appears to contain a cell population which synthesizes nonsecretory Ig. The structure of this Ig was studied by specific serological precipitation and by SDS-acrylamide gel electrophoresis. The H chains of this nonsecretory Ig are serologically related to micro-chains and exhibit a smaller molecular weight (i.e., approximately 50,000) in SDS-acrylamide gel electrophoresis than H chains of IgG and IgM synthesized by the spleen cells (i.e., approximately 70,000).

Animals↗
PubMed1972

Morphological and functional studies of fetal thymus transplants in mice.

The fetal thymus at 13 days of gestation withstands transplantation and develops normally under the renal capsule of a syngenic host. Distinct differences were observed between the fetal thymus grafts and grafts from neonatal or adult thymus donors. The fetal thymus graft did not undergo the rapid and severe necrosis observed when adult thymus was grafted. Furthermore, when thymuses were transplanted into allogenic recipients, rejection was delayed. The fetal thymus was as effective as the adult thymus in restoring syngenic neonatally thymectomized mice and far superior to adult thymus when grafted into allogenic recipients. These observations seem relevant to clinical efforts to restore immunocompetence in patients with congenital absence of the thymus.

Animals↗