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H Ramseier

Publications and source records attributed to H Ramseier.

47 records · Page 3Linked to original sources
PubMed1969

Quaitative studies on antigenic recognition. I. Immunological and nonimmunological parameters of the response.

Lymphoid cells from normal animals from two genetically alien but isogenic strains of mice or rats elaborated a factor into the medium during in vitro cultivation. Similarly, lymphoid cells from specifically presensitized animals mixed and cultivated with donor-type lymphoid cells, as well as normal or specifically immunized mouse spleen cells exposed to heterologous red blood cell antigens, formed this factor. Culture supernatants of genetically identical lymphoid cells lacked activity. This factor was measured by its ability to induce accumulations of polymorphonuclear cells following injection into the skin of normal hamster hosts. Gentle trypsinization of excised 24 hr cutaneous reactions permitted quantitative estimation of the number of polymorphonuclear cells accumulated and, therefore, of the activity of the factor. The factor present in culture fluids could be defined as a product of antigenic recognition (PAR). PAR was formed only when immunologically competent cells were exposed to cells carrying histocompatibility antigens of recognizable foreignness. This view was based chiefly on the observation that, whereas lymphoid cells from specifically tolerant mice failed to recognize the paralytogen, they did recognize antigens of an unrelated mouse strain. In addition, immunocompetence was of paramount importance, since cocultivation of immunologically incompetent, yet strongly incompatible, rat thymocytes did not result in the formation of PAR. Formation of PAR was observed in very simple media. A source of energy and a suitable culture vessel were found to be the only essential nonimmunological factors for PAR to be elaborated. The presence of inhibitors of glycolysis in the medium during cultivation of mixtures of immunocompetent cells of disparate origin severely inhibited the recognition process. With cell mixtures of the immunological one-way variety, treatment of aggressor cells with inhibitors of glycolysis or of protein synthesis interfered with antigenic recognition, whereas similar treatments of the target cells were without effect. The findings presented sustain the thesis that the elaboration of PAR is a very early event in the immune process.

Animals↗
PubMed1967

Leukotactic factor elaborated by mixtures of genetically dissimilar cells.

Mixtures of immunologically competent cells, from genetically dissimilar donors from inbred strains of mice, rats, or Syrian hamsters, cultivated in vitro elaborate into the medium a factor capable of attracting polymorphonuclear cells when it is injected into the skin of irradiated hamsters. Supernatant medium of cultured node cells from genetically identical donors contains no leukotactic activity. The degree of the cell accumulation seemed to parallel closely the degree of histoincompatibility.

Animals↗
PubMed1966

Studies on delayed cutaneous inflammatory reactions elicited by inoculation of homologous cells into hamsters' skins.

The intracutaneous inoculation of lymph node cell suspensions from normal hamsters into normal, homologous hosts causes the development of delayed inflammatory reactions, normal lymphocyte transfer (NLT) reactions, the intensities of which reflect the antigenic disparity between donor and recipient. The immunogenetic situations in which they occur indicate that these reactions are due to sensitization in situ on the part of inoculated immunologically competent cells against alien antigens of the host. They are graft versus host reactions. If hamsters are sensitized by cellular or solid tissue homografts and then challenged intracutaneously with lymphoid or epidermal cells from the donor strain, direct reactions are provoked. A positive correlation exists between the development of transplantation immunity and the capacity to give direct reactions. The sensitivity responsible for direct reactions can be suppressed by irradiation or administration of cortisone, and it is transferable by means of viable lymphoid tissues or cells but not by means of serum. Intracutaneous inoculation of viable node or splenic cells from specifically sensitized hamsters into hosts of the donor strain incites transfer reactions, the intensities of which depend upon the number of cells transferred and the level of sensitivity in the animal that provided them. These reactions are not incitable by thymocytes, by killed lymphoid cells, or by serum. Transfer reactions differ from NLT reactions only on a quantitative and chronologic basis. However, a sharp experimental distinction can be drawn between them. For example, if normal MHA node cells and node cells from MHA hamsters sensitized against CB antigens are injected into the skins of MHA's tolerant of CB tissue, only the sensitized cells incite reactions. Both direct and transfer reactions are highly specific immunologically. The inability of node cells to incite NLT or transfer reactions in heavily irradiated hosts and other findings sustain the thesis that it is host cells of hematologic origin, rather than indigenous skin cells, that contribute the antigenic stimulus required for these reactions. All the findings presented are consistent with the hypothesis that the various delayed inflammatory reactions described are manifestations of immunological responses on the part of immunologically competent cells against alien transplantation antigens.

Animals↗
PubMedDate not supplied

Release of IL-1 and IL-2 and expression of IL-2 receptors as a function of postnatal age and sex.

Release patterns of the mitogen-induced cytokines IL-1 and IL2 by Long Evans rat unfractionated spleen cells, as well as expression of IL-2R on such cells at different postnatal days (neonatal to adult) were studied for female and male rats. IL-1 release was found to be low but in a more or less steady fashion in cells of both sexes over the entire period. However, IL-2 synthesis increased from an almost undetectable level up to a significant secretion at the time of weaning and continued to increase in female but not male spleen cells. IL-2 receptors were found to be expressed in moderate amounts already at early postnatal days and up to weaning. Thereafter, the synthesis of IL-2R followed a course essentially similar to that of IL-2, i.e. higher for female than for male cells. In the female rats, a hormonal influence was observed on the formation of IL-1 and IL-2 but not on the expression of IL-2R.

Aging↗