Influence of human T lymphocytes identified by antibodies to dipeptidyl peptidase IV on differentiation of human B lymphocytes stimulated with Staphylococcus aureus Cowan I and pokeweed mitogen

The influence of human T lymphocytes expressing the enzyme dipeptidyl peptidase IV (DPP IV) was investigated with respect to human peripheral B-lymphocyte differentiation. B cells stimulated with pokeweed mitogen in the presence of DPP IV-positive T cells produced high amounts of immunoglobulin. Moderate amounts of immunoglobulin could be measured when B cells were cultured in the presence of DPP IV-negative T cells. DPP IV defines a T-cell subset partially overlapping the subsets characterized by the differentiation antigens Leu 3a (helper/inducer) and Leu 2a (suppressor/cytotoxic). DPP IV-positive T cells exert, in contrast to DPP IV-negative T cells, high interleukin-2 activity after stimulation with phytohemagglutinin and pokeweed mitogen. To further functionally characterize DPP IV-positive and DPP IV-negative T cells, the helper effects of Leu 3a-positive T-cell subsets, differing in DPP IV expression, were investigated in pokeweed mitogen- and Staphylococcus aureus-driven B-cell differentiation systems. After pokeweed mitogen stimulation, immunoglobulin production was markedly reduced when B cells were cultured in the presence of Leu 3a-positive T cells expressing DPP IV (DPP IV+/Leu 3a+). In contrast, high amounts of immunoglobulin were produced in cultures with Leu 3a-positive but DPP IV-negative T cells (DPP IV-/Leu 3a+). This difference in immunoglobulin production of B cells cultured with DPP IV+/Leu 3a+ and DPP IV-/Leu 3a+ T cells could not be observed in Staphylococcus aureus-stimulated cultures. Here, both T-cell subsets supported terminal differentiation of B cells. We conclude that in the pokeweed mitogen-driven culture systems, DPP IV+/Leu 3a+ and DPP IV-/Leu 3a+ T cells may differ in the production of growth and/or differentiation factors distinct from interleukin-2.     

Impaired natural killer cell function in hemophiliacs with or without continuous substitution

In the present study, 28 hemophiliacs substituted continuously and 5 hemophiliacs who had received almost no blood products were investigated. Cells of OKT 3+, OKT 4+, and OKT 8+ subsets were counted. Percoll separated fractions of peripheral blood mononuclear cells were examined by morphological criteria and were tested for NK cell activity. We found that the NK cell activity of both groups of hemophiliacs was decreased on testing Ficoll separated cells or low density Percoll separated cells. Normal NK cell activity was found in medium density cells of hemophiliacs. Two possible explanations are discussed: first, the NK cell activity may be suppressed in hemophiliacs and secondly, there may be a block in maturation of NK cell activity. It is unlikely that chronic substitution by blood products counts for these alterations. The possible role of chronic infections is discussed.     

Genetische Untersuchungen zur Resistenz der Gerste gegen Gelbrost (Puccinia striiformis West.)

Zusammenfassung Fünf Sommergersten, die gegen Rasse 24 von Puccinia striiformis resistent sind, wurden in fast allen möglichen Kombinationen miteinander und mit drei anfälligen Formen gekreuzt. Die F ₂-Generationen, in zwei Fällen auch die F ₃, wurden im Gewächshaus mit Rasse 24 infiziert. Zusätzlich konnten F ₂-Generationen einiger Kreuzungen auch auf dem Feld mit Rasse 24 geprüft werden. Eine sichere Klassifikation und damit die eindeutige Analyse der Ergebnisse war nur im Gewächshaus möglich. Die Feldversuche stützen zwar diese Ergebnisse, hätten aber allein keine sicheren Schlüsse erlaubt.Die Resistenz aller fünf untersuchten Gersten ist monogen rezessiv bedingt. Drei von ihnen sind bezüglich des Resistenzgens allel: Bigo — yr, Ab. 14 — yr, BBA 2890 — yr. In Abed Binder 12 liegt yr2 vor, in I 5 yr3. Die Ergebnisse deuten auf Unabhängigkeit der drei Gene, enge Kopplung kann ausgeschlossen werden.

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Genetic studies on the resistance of barley to yellow rust (Puccinia striiformis West.)

Summary Five spring barley varieties resistant to race 24 of Puccinia striiformis were crossed with each other and with three susceptible varieties (Table 1) in almost all possible combinations. The F ₂ generations and in two cases also the F ₃, were inoculated in the greenhouse with race 24. F ₂ generations of some of the crosses were, in addition, tested with race 24 in the field. Dependable classification of resistance and, consequently, unambiguous interpretation of results was possible only for the experiments carried out in the greenhouse. Although the field tests confirmed these results, they would not have been conclusive by themselves.The resistance of all of the five varieties studied is due to single recessive genes (Table 2). Three of the varieties have alleles at the same locus, the other two varieties have other resistance genes (Tables 3 and 4): Bigo — yr, Ab. 14 — yr, BBA 2890 — yr; Abed Binder 12 — yr2; I 5 — yr3. The results suggest that the three genes are inherited independently, close linkage can be excluded.

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Angenommen durch H. Stubbe     

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