Differential Effects of Immunosuppressants on Lymphocyte Function

In vitro and in vivo parameters of T lymphocyte function were evaluated in guinea pigs following treatment with the “cycle-active” drugs, 6-mercaptopurine (6MP) and methotrexate, and the “non-cycle-active” alkylating agent, cyclophosphamide. Commencing at the time of sensitization to tuberculin protein, animals were treated with an 8 day course of one of the cytotoxic drugs. This regimen either reduced or abolished the cutaneous response to PPD. The two cycle-active drugs inhibited the in vitro lymphoproliferative response to PPD and suppressed the elaboration of migration inhibition factor (MIF) by lymph node cells. However, these agents did not reduce blood lymphocytes, deplete the cellularity of the thymic dependent areas of peripheral tissues, or alter the in vitro response of lymph node cells to the nonspecific mitogen PHA. In contrast, treatment with cyclophosphamide was associated with a reduction in peripheral blood and tissue lymphocytes and impaired responses to PHA by residual lymph node cells. In vitro proliferative responses to PPD were inhibited but the capacity of lymph node cells to elaborate MIF was not suppressed. In addition to their effects on antigen-reactive lymphocytes, all three drugs significantly reduced the number of macrophages in induced peritoneal exudates. With respect to immunosuppressive activities, results of these investigations suggest that the noncycle-active agents affect both intermitotic and dividing T lymphocytes without impairing certain intermitotic functions of residual cells. The cycle-active drugs have a more restricted toxicity limited to those T lymphocytes which have been stimulated to undergo active DNA synthesis by antigenic challenge

El ayuno estimula los mecanismos inmunitarios efectores en los individuos obesos

Estudio de los parámetros inmunitarios en 15 sujetos obesos, antes y después de un ayuno de 14 días

Cycling Characteristics of Human Lymphocytes In Vitro

Abstract The cycling characteristics of human peripheral blood lymphocytes in phytohemagglutinin-stimulated cultures were examined by means of a new technique employing radioautographic methods which assay the fraction of cells whose nuclei contain DNA polymerase utilizing exogenous and/or endogenous DNA primer-template capability. The fraction of cells labeled by these techniques increases 5-11 hr prior to the onset of DNA synthesis. Estimates of cell cycle time, G1 time, and fraction of cycling cells are made for the first 4 days in culture. Evidence is presented to support the hypothesis that daughter cells of the first divisions may be retired from cycle by virtue of loss of primer-template availability, rather than by loss of DNA polymerase

Psychosocial Variables and the Course of Cancer

The data reported by Cassileth et al. (June 13 issue)1 provide potentially valuable information on the importance of psychosocial factors in surviving advanced malignant disease. I do not agree, however, that this study supports the conclusion, as the authors state, that "the inherent biology of the disease alone determines the prognosis...." The seven factors used to construct the psychosocial index were selected because of their association with survival or longevity in previous studies that were conducted, for the most part, in selected healthy populations.</p