Stages Of Immune Response Research Articles

Cytokine-induced survival of activated T cells in vitro and in vivo.

Many antigen-specific T cells die after exposure to antigen in animals. These cells also die if they are isolated from animals shortly after activation and cultured. Various cytokines were tested for their ability to interfere with this in vitro death. Surprisingly, tumor necrosis factor alpha and other inflammatory cytokines did not prevent the in vitro death of activated T cells, even though these cytokines do prevent activated T cell death in animals. Therefore, the inflammatory cytokines probably act on T cells in vivo via an intermediary factor. Four cytokines, interleukin (IL)-2, IL-4, IL-7, and IL-15, did prevent activated T cell death in vitro, with IL-4 and IL-15 more effective than IL-2 or IL-7. These cytokines share a component of their receptors, the common gamma chain, gammac. Therefore, their collective ability to protect activated T cells from death may be mediated by signals involving gammac. To assess their activity in vivo, two of the cytokines, IL-2 and IL-4, were expressed in animals at local sites of superantigen responses. Both cytokines increased the numbers of T cells found at the local sites 14 days later. Interleukin 4 was more effective than IL-2, even though IL-2 stimulates T cell proliferation better than IL-4. This result suggested that IL-4 and related cytokines can promote T cell survival in vivo as well as in vitro. The ability of these cytokines to prevent the death of activated T cells may be important at certain stages of immune responses in animals.

Changes in the content of Met-enkephalin in different brain structures during the development of immune response

Changes in the content of the opiate peptide Met-enkephalin at the early stages of immune response are studied in different structures of rats brain 20 min and 24 h after immunization with sheep erythrocytes.

Cytotoxic and antibacterial properties ofMytilus galloprovincialis,Ostrea edulisandCrassostrea gigas(bivalve molluscs) hemolymph

Mussel (Mytilus galloprovincialis) plasma contains cytotoxic activity against both vertebrate (erythrocytes and mouse tumour) and protozoan cells. Procaryotes (Escherichia coli and Vibrio alginolyticus) were not sensitive to the cytotoxicity. The activity was still present in dialyzed samples but was inhibited by heating at 45 °C. Large individual variability which was not correlated with protein concentration and an increasing number of reactive specimens following injection, suggested that naive mussels were in various stages of immune response. Purification by anion exchange chromatography followed by gel filtration revealed a 320 kDa cytotoxic polymeric protein that acts through a polymerization process after binding onto target cell membranes as revealed by ultrastructural observation.

Maturation of the humoral immune response as an optimization problem

Efficient immune response often depends on the production of high affinity antibodies. We show analytically that the optimal strategy for a fast production of high affinity antibodies is to utilize a step-function mutation rate, i.e. a minimal mutation rate in early stages of the immune response, followed by a discontinuous switch to the maximal possible rate when the proliferating population of B-cells exceeds a threshold value. Our results are in accordance with the biological observations concerning the time of onset of the hypermutation process, and with the mutation rate during the later stages of the primary immune response. Indeed the hypermutation process plays a crucial role in responding to a prevailing pathogen at each round of immune response, and not only for coping with future infections. Moreover, as the effect of hypermutations is shown to be crucially dependent on the number of proliferating B-cells, its onset is not expected to depend on an external signal, but rather to be related to the clone's age. This suggests that the onset is host species specific, rather than pathogen specific. Another implication of the present results is that activation of hypermutations before the B-cell population has reached the critical size may impede the efficiency of the response.

Studies on anti-infective mechanism of the traditional Chinese medicinal preparation “Anti-inflammatory Agent No. 6” — Its influence on immune functions of mice

The traditional Chinese medicinal preparation “Anti-inflammatory Agent No.6” (for injection) could raise the phagocytic index and phagocytic rate of the peritoneal macrophages by 2.5 and 3 times respectively in experimental mice, and it could also enhance the activity of complement alternative pathway evidently. However, the serum lysozyme level did not rise unless a large doss of it was given. It was also shown by the measurement of the spleen cell immune specific RFC (IRFC), quantitative hemolysis of SRBC and anti-SRBC antibodies that this preparation promoted the specific humoral immunity at different stages of immune response in mice. The results of cellular immunity tests also revealed that it had an obvious influence upon the delayed hypersensitive reaction as well as on the number of ANAE-positive cells in the peripheral blood. The preparation was proved to have a good anti-infective effect, for it could regulate and enhance a variety of immune functions.