PubMed Health⌕ Search

Biomedical subjects

D K Dennison

Publications and source records attributed to D K Dennison.

5 recordsLinked to original sources
PubMed1979

Interaction between T cells and non-T cells in suppression of cytotoxic lymphocyte responses.

Generation of cytotoxic T lymphocytes (CTL) in mixed leukocyte cultures was suppressed by a factor elaborated by alloantigen-activated T cells. This suppressor factor, CTL-TsF, in contrast to a factor that suppresses proliferative responses in mixed leukocyte reactions (MLR-TsF), was effective only when added during the first 24 hr of a 6-day-culture period. Moreover, removal of CTL-TsF 24 hr after culture initiation failed to restore CTL responses. CTL activity could be rescued from suppressed cultures, however, by addition of 2-mercaptoethanol on days 3 or 4. Similarly, transfer of nonadherent cells at 3 or 4 days from cultures treated with CTL-TsF to cultures of adherent cells initiated in control factor restored CTL responses. Mixing experiments with cells pulsed with CTL-TsF for 4 hr at culture initiation identified a target of CTL-TsF as a Thy-1 negative cell that was adherent to plastic and to Sephadex G-10. Suppression was not due to interference with physiologic accessory cell function, but more likely was accomplished via a negative signal from CTL-TsF-pulsed cells. The results thus suggest that CTL-TsF acts early, but reversibly, in the CTL differentiative process via a second suppressor effector cell, possibly a macrophage.

Animals↗
PubMed1977

The level of FC receptor leukocytes in primary and secondary skin allograft recipients.

DA (Ag-B4) rats were grafted with allogeneic Lewis (Ag-B1) skin on the region of the thorax drained by the left brachial and axillary lymph nodes. A DA isograft was placed on the right side of the thorax. From 1 to 14 days after grafting the rats were either given injections of colloidal carbon, killed, and spleen and lymph nodes were assayed for noncarbon-containing Fc rosette-forming leukocytes (RFL), or allowed to complete rejection of the graft. In order to assess secondary allograft rejection within the latter animals after the grafted areas was healed, a second Lewis allograft was placed in the same region as the first and another DA isograft on the right side. Compartmental Fc RFL were enumerated 2 to 16 days thereafter by rosette formation with erythrocyte-antibody. The regional lymph nodes of animals rejecting a primary allograft exhibited a significantly (P less than 0.05) higher level of Fc RFL compared with their contralateral controls. These higher levels were evident on days 6 to 8 and disappear by day 10. However, animals undergoing a secondary allograft response exhibited significant differences by day 4. A greater density of Fc RFL were also evident in cryostat sections of the graft bed of allografts as opposed to isografts.

Animals↗