Related Experiment Video

Updated: Aug 8, 2026

Rapid Quantification of Mitogen-induced Blastogenesis in T Lymphocytes for Identifying Immunomodulatory Drugs
08:13

Rapid Quantification of Mitogen-induced Blastogenesis in T Lymphocytes for Identifying Immunomodulatory Drugs

Published on: December 27, 2016

Cyclosporin A directly inhibits human B-cell proliferation by more than a single mechanism

A C Hannam-Harris, D S Taylor, P C Nowell

    Journal of Leukocyte Biology
    |August 1, 1985
    PubMed

    Cyclosporin A (CsA) is a potent immunosuppressive agent that inhibits T-cell proliferation and lymphokine production. There is less information on the direct effect of CsA on B-cells. We investigated the proliferative responses of human tonsillar B-lymphocytes to a "T dependent" mitogen, pokeweed mitogen (PWM), and to a "T independent" mitogen, Staphylococcus aureus (SA). Both responses were strongly inhibited by CsA. Nonspecific cytotoxicity was ruled out, and the inhibition was not reversed by adding IL1, IL2, or BCGF individually or in combination. Maximal inhibition of the PWM response occurred when CsA was added early in the culture period. Cyclosporin A added 18 hours after the start of culture was less effective, and adding CsA after 36 hours resulted in only minimal inhibition. However, with SA as mitogen, addition after 36 hours still affected substantial inhibition. These results, on the time of action and resistance to reversal by exogenous growth factors, suggest that CsA can directly inhibit human B-cells by a mechanism similar to its action on T-lymphocytes, blocking an early event critical to entry into cell cycle, but an additional mechanism of inhibition later in the cell cycle may also operate when the proliferative signal is provided by the T-independent mitogen SA.

    More Related Videos

    Identification of Mediators of T-cell Receptor Signaling via the Screening of Chemical Inhibitor Libraries08:49

    Identification of Mediators of T-cell Receptor Signaling via the Screening of Chemical Inhibitor Libraries

    Published on: January 22, 2019

    Structure-Guided Design and Development of Novel Cyclophilin A Inhibitors and Ganoderiol-F Derivatives: An In-Silico Approach10:01

    Structure-Guided Design and Development of Novel Cyclophilin A Inhibitors and Ganoderiol-F Derivatives: An In-Silico Approach

    Published on: June 23, 2026

    Related Concept Videos

    Negative Regulator Molecules01:23

    Negative Regulator Molecules

    Positive regulators allow a cell to advance through cell cycle checkpoints. Negative regulators have an equally important role as they terminate a cell’s progression through the cell cycle—or pause it—until the cell meets specific criteria.
    Positive Regulator Molecules02:39

    Positive Regulator Molecules

    Mitotic cell division results in daughter cells that exactly resemble the parent cell. However, errors in the DNA replication or distribution of genetic material may lead to genetic mutations that may be passed down to every new cell formed from the resulting abnormal cell. Propagation of such mutant cells is restricted through checkpoint mechanisms present at different stages of the cell cycle. These checkpoints involve regulator molecules that either promote or demote cell cycle events.
    Inhibition of Cdk Activity02:34

    Inhibition of Cdk Activity

    The orderly progression of the cell cycle depends on the activation of Cdk protein by binding to its cyclin partner. However, the cell cycle must be restricted when undergoing abnormal changes. Most cancers correlate to the deregulated cell cycle, and since Cdks are a central component of the cell cycle, Cdk inhibitors are extensively studied to develop anticancer agents. For instance, cyclin D associates with several Cdks, such as Cdk 4/6, to form an active complex. The cyclin D-Cdk4/6 complex...
    Inhibition of CDK Activity02:34

    Inhibition of CDK Activity

    The orderly progression of the cell cycle depends on the activation of Cdk protein by binding to its cyclin partner. However, the cell cycle must be restricted when undergoing abnormal changes. Most cancers correlate to the deregulated cell cycle, and since Cdks are a central component of the cell cycle, Cdk inhibitors are extensively studied to develop anticancer agents. For instance, cyclin D associates with several Cdks, such as Cdk 4/6, to form an active complex. The cyclin D-Cdk4/6 complex...
    Molecular Factors Affecting Cell Division01:27

    Molecular Factors Affecting Cell Division

    Several external and internal factors influence the initiation and inhibition of cell division. For instance, the death of nearby cells or the release of human growth hormone (hGH) promotes cell division. In contrast, lack of hGH or crowding of cells can inhibit cell division.
    Several proteins function as internal regulators to ensure each cell cycle stage is completed faithfully before proceeding to the next. Regulator molecules may act directly or influence the activity or production of other...
    Antifungal Agents01:15

    Antifungal Agents

    Amphotericin B is a broad-spectrum antifungal agent that exploits structural differences between fungal and mammalian cell membranes. Its amphipathic structure—featuring a hydrophobic polyene-lactone ring and a hydrophilic region containing mycosamine and carboxylic acid groups—enables selective binding to ergosterol, a sterol predominantly found in fungal plasma membranes. This selective interaction underlies the drug’s antifungal activity, although weak binding to cholesterol contributes to...