Ontogeny of the ferret humoral immune response.

Infant ferrets are born with nearly undetectable immunoglobulin levels, but by 9 days of age the infant ferret serum contains 77, 29, and 13% of adult mean serum levels of IgG, IgA, and IgM. Transmucosal uptake of IgG by the infant ferret occurred for the first 30 days of life. The specific anti-respiratory syncytial virus neutralizing titer of whole milk was 5.5 times higher than maternal serum despite a lower concentration of immunoglobulins in the milk.     

Role of thymus-eicosanoids in the immune response.

The present review deals with the role(s) of thymus-eicosanoids in the immune response. It reports the production of cyclooxygenase and lipoxygenase metabolites of arachidonic acid by cells of the thymus microenvironment and the role(s) of these eicosanoids in the differentiation and the maturation of immature T-cells. The possibility that these products may be involved in tolerance to self is discussed. Briefly, it is likely that cells from the monocyte-macrophage lineage which constitute a part of the thymus microenvironment could contribute to the education of immature thymocytes by both presenting self-antigens and producing eicosanoids. Tolerance to self might result from PGE2-driven apoptosis and/or LTB4-induced generation of suppressor cells.     

Experimental immune complex glomerulonephritis in the mouse with two types of immune complexes.

Immune complex glomerulonephritis was induced in three groups of mice by long-term immunization. Two antigens of similar molecular weight were used. The first group was immunized with ferritin (mol wt 480,000). In altered glomeruli deposits of immune complexes were seen in the subendothelial and subepithelial spaces of the glomerular basement membrane (GBM) and in the mesangium. The immune complex deposits were formed by amorphous matrix with marked dense molecules of ferritin. The second group was immunized with human fibrinogen (mol wt 450,000). The immune complex deposits were present in the intramembranous, subepithelial and subendothelial spaces of the GBM and in the mesangium. These deposits were relatively less electron-dense and had a fine granular structure. The third group of mice were immunized with both ferritin and fibrinogen simultaneously. Two types of deposits situated subendothelially in the GBM and in the mesangium were seen in one animal of this group. One type of deposit resembled structurally the ferritin-antiferritin complex deposits, the other resembled the fibrinogen-antifibrinogen complex deposits. The individual deposits in the GBM and in the mesangium formed discrete homogeneous masses. The two types of deposit were occassionally in direct contact with one another, but were more often completely separate and were never mixed. It can be assumed that in at least some phase of the experiment both types of complex were present in the circulating blood simultaneously. However, since none of the complexes deposited in the GBM or in the mesangium were mixed, it seems probable that each type of complex is deposited separately in the form of "clusters" composed of a single type of complex. The phagocytic activity of mesangial cells of animals with complex glomerulonephritis was not increased when compared with control animals.     

Site-specific recombination in the immune system.

Site-specific DNA recombination has been identified in a wide variety of biological systems. In vertebrates, however, the only identified use of this genetic device is in the immune system. Here it plays a critical role in generating a diverse repertoire of surface receptors to intercept invading microbes and parasites. The mechanism and orchestration of this reaction are intriguing and are relevant to a broad array of related biological and biomedical issues.     

Hibernation alters the frog's immune system.

The lymphomyeloid organs and blood leukocyte populations of the leopard frog, Rana pipiens, undergo conspicuous changes during hibernation at 4 degrees C. Within the blood, spleen, thymus, jugular bodies, and bone marrow there was a progressive loss of hemopoietic populations resulting in a marked lymphocyte depletion. Termination of the 135-day hibernation period resulted in the restoration of all hemopoietic elements in the blood and lymphomyeloid organs within 30 days. Frogs subjected to experimental hibernation and immunized showed weakened immune responses when brought from the hibernaculum. Plaque-forming cells (PFC) were lower in spleen, jugular bodies, and bone marrow, and serum antibody titers were also lower. Although the kinetics of the primary responses were essentially the same, the secondary responses differed suggesting major rearrangements with respect to the numbers of cells and their function in secreting antibody. The apparent lymphocyte aplasia may contribute to the absence of immunological responsiveness during periods of hibernation.     

Composition of the immune system of allophenic mice.

Mice were immunized with antigen (Rabbit Fab' fragments) attached to syngeneic, or f₁ (semi-syngeneic) irradiated spleen cells. Specific anti-rabbit Fab' plaque forming cell numbers showed that the response towards antigen on syngeneic or F₁ cells, was significantly lower than that towards the same antigen on allogeneic cells. By subsequent in vitro incubation of immune spleen cells with antigen followed by plaque assay, it was found that those spleen cells exhibiting lowered plaque forming cell numbers initially, (i.e., those mice immunized with antigen on syngeneic or F₁ cell surfaces) showed, after incubation, a response equal to or greater than those cells which initially (before in vitro incubation) demonstrated a larger response (i.e. those mice immunized with antigen on allogeneic cells).