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Biomedical subjects

Z Trnka

Publications and source records attributed to Z Trnka.

At least 37 records · Page 2Linked to original sources
PubMed1979

The migration of lymphocytes in the fetal lamb.

The migration of 51Cr-labeled autologous lymphocytes from intestinal or prescapular lymph was compared in fetal lambs and adult sheep. A subpopulation of lymphocytes present in intestinal lymph of adults which migrated to the small intestine was not found in fetal intestinal lymph. There were marked differences in the migration of fetal and adult lymphocytes to the lungs and liver. In spite of the absence of circulating antibodies or immunoglobulins and of extrinsic antigen in the immunologically virgin sheep fetus, the circulation of lymphocytes through the spleen and lymph nodes of fetal lambs was more intense than in the adult.

Animals↗
PubMed1979

Changes in mixed lymphocyte culture-reactive lymphocytes following alloimmunization of single lymph nodes in sheep.

When an "isolated" single lymph node is challenged with irradiated allogeneic lymphocytes, there is a change in the reactivity of the lymphocytes flowing out of the node when they are cultured in vitro in unidirectional mixed lymphocyte cultures (MLC) against the immunizing lymphocytes. These changes in the reactivity of the recipient lymphocytes are shortlived, follow a set time sequence in relation to the cell traffic changes accompanying the immune response, are the property of small lymphocytes and not blast cells, are exhibited by surface Ig-negative cells, and they are specific for the donor lymphocytes. It is suggested that antigen causes the selective retention of antigen-specific lymphocytes within the stimulated node followed by the proliferation and differentiation of large numbers of antigen-specific cells, which then leave the lymph node as small lymphocytes.

Animals↗
PubMed1979

Collection of lymph from single lymph nodes and the intestines of fetal lambs in utero.

Techniques for establishing chronic lymphatic fistulae in the intestinal and prescapular lymphatic ducts of fetal lambs during the test third of gestation are described. Despite the absence of antibody, immunoglobulin and extrinsic antigen, the number of recirculating lymphocytes increases considerably through gestation. Both thymus-derived and surface Ig-bearing B lymphocytes are present in the fetal recirculating pool and they appear to increase in number at the same rate.

Animals↗
PubMed1978

Induction of haemolytic plaque-forming cells with sheep lymphoid cells in vitro.

The in vitro induction of specific primary and secondary immune responses in sheep lymph node cell suspensions is described and suitable culture conditions determined. The induction of primary immune responses required supplementation of the culture medium with antigen-absorbed homologous serum or lymph, whereas the requirements for the induction of a secondary response were less stringent. The addition of 2-mercaptoethanol to the medium was required. The amounts of heterologous erythrocytes used for immunization were critical and optimal responses were obtained when 50 microleters of a 1% suspension were added to 1 ml cultures. Lymphocyte densities of about 5 X 10(6)/ml were found optimal in primary immune responses in vitro. Less than 2 X 10(6) cells/ml rarely gave rise to plaque-forming cell (PFC) generation, whereas densities of 10 x 10(6) and above reduced the number of PFC obtained per number of cultured cells. Lymphocytes obtained from the efferent lymph draining lymph nodes previously immunized with heterologous erythrocytes were found to generate PFC in vitro when specific antigen was added to the cultures, but attempts to generate PFC in vitro with cells from efferent lymph draining non-immunized nodes failed.

Animals↗
PubMed1978

Behaviour of sheep-immunoglobulin-bearing and non-immunoglobulin-bearing lymphocytes isolated by nylon wool columns.

The technique of separating lymphocytes on nylon wool columns has been applied to sheep lymphocytes obtained from efferent lymph. The non-immunoglobulin-bearing (sIg-) lymphocytes which pass through the column were MLR-reactive, responsive only to T cell mitogens, and migrated in vivo like T lymphocytes described in rodents. Immunoglobulin-bearing (sIg+) lymphocytes were MLR-non-reactive, responsive to lipopolysaccharide and migrated in vivo like B lymphocytes in rodents. It is considered that the majority of sIg- lymphocytes obtained in this way are T lymphocytes and the majority of sIg+ lymphocytes are B lymphocytes.

Animals↗
PubMed1977

Two distinct pools of recirculating T lymphocytes: migratory characteristics of nodal and intestinal T lymphocytes.

A pronounced asymmetry in the recirculation from blood to lymph of resting small recirculating T lymphocytes is described. When 51Cr-labeled small T-recirculating lymphocytes (TRL) from intestinal lymph were infused intravenously their relative recovery in intestinal lymph was about twice that in nodal lymph. In contrast, the relative recovery in nodal lymph of 51Cr-labeled nodal TRL was twice that in intestinal lymph. Intestinal TRL migrated in large numbers through the small intestine. Nodal TRL did not. It is proposed that the pool of recirculating small T lymphocytes consists of two major subdivisions, an intestinal pool and a nodal pool. The nodal circulation comprises small TRL which traverse PCV in all lymph nodes (LN) but not the small intestine. The intestinal circulation comprises small TRL which do not traverse PCV in LN, but which do recirculate through the small intestine from which they pass via afferent lymphatics to the mesenteric LN and subsequently via the thoracic duct into the blood. It is suggested that the intestinal circulation is present in the fetus and that its initial development is independent of extrinsic antigen.

Animals↗
PubMed1977

The appearance of non-specific antibody-forming cells in the efferent lymph draining antigen-stimulated single lymph nodes.

Immunization of single lymph nodes with various antigens led to the appearance of cells in the efferent lymph that secreted antibody specific for the antigen which induced their formation and for a number of unrelated, non-crossreacting antigens. Immunization of single lymph nodes with mitogens led to the appearance of cells secreting antibodies specific for an even greater number of antigens, including one (TNP) that in all probability is not present in the animals' natural environment. When the node was primed with one antigen, a subsequent challenge with an unrelated antigen 12 weeks later led to the appearance of greater numbers of cells containing and secreting antibody against the previously experienced antigen, than was the case in unprimed lymph nodes. These findings indicate that the immune response to antigen provokes the maturation of lymphocytes of specificities unrelated to that of the injected immunogen. Such a mechanism may be important in maintaining immunological memory. Mitogens may directly activate lymphocytes into maturation and expression as antibody-secreting cells, whereas antigens appear to act indirectly.

Animals↗
PubMed1976

The effects of antigen on the migration of recirculating lymphocytes through single lymph nodes.

The increased input of RL into LN starts within 3 h after antigenic stimulation and is due to an increase in the number of RL passing through a LN. It is not associated with an altered transit time through a LN of the majority of RL and it cannot occur in the absence of high endothelial PCV. The immediate decrease in the output of RL from an antigen-stimulated LN is due to a delay in the exit from that LN of RL which had entered the LN before antigen was given. The decrease in cell output from a LN after antigen administration affects blast cells produced within the LN as well as small lymphocytes and is not specific for RL. There are at least two distinct mechanisms controlling the migration of RL through an antigen-stimulated LN. The first controls the increased input of RL which occurs only through high endothelial PCV. The second controls the immediate decrease in cell output, which although it does not occur at the level of the high endothelial PCV, can only occur in organized lymphoid tissue. The increased input of RL into an antigen-stimulated LN and the decreased cell output from the LN can occur independently and are possibly controlled by different mechanisms.

Animals↗
PubMed1976

Antipolysaccharide antibodies of restricted heterogeneity secreted by a single lymph node.

Immune responses which give rise to the synthesis of antibodies of restricted heterogeneity can be reproducibly induced in rabbits and mice by streptococcal polysaccharide antigens (1,2). While these reports have demonstrated clonotype restriction in the immune serum of rabbits and mice, they give little information with respect to the clontype restriction in a single reaction site of organized lymphoid tissue, for example a single lymph node. The kinetics of immune responses in lymph nodes in situ have been studied in sheep using a variety of antigens (3-6), and a substantial body of information is available on the changes in cell output, cell type, and the number of antibody-secreting cells which occur within the efferent lymph of antigen-stimulated lymph nodes. However, there is no information with respect to the amount and the heterogeneity of antibody that is secreted by the lymph node or cells within the efferent lymph. In the present report we have examined the temporal sequence of clonal restriction in the efferent lymph of individual sheep popliteal lymph nodes undergoing an immune response to the streptococcal group A-variant polysaccharide (Av-CHO).

Animals↗