Activation of a Macrophage by a Th1 Lymphocyte

Fig. 2: Activation of a Macrophage by a T_H1 Lymphocyte

1. Engulfed bacteria inside a phagosome or a phagolysosome.
2. An activated T_H1 lymphocyte binds to a peptide/MHC-II complex on a macrophage by way of its TCR and CD4 molecule. Co-stimulatory molecules such as CD40L on the T_H1 cell then bind to CD40 on a macrophage.
3. This triggers the T_H1 lymphocyte to secrete the cytokine interferon-gamma (IFN-γ) that binds to IFN-γ receptors receptors on the macrophage.
4. The IFN-γ activates the macrophage enabling it to produce more hydrolytic lysosomal enzymes, nitric oxide, and toxic oxygen radicals that destroy the microorganisms within the phagosomes and phagolysosomes.

Illustration of Binding of Peptide Epitopes from Endogenous Antigens to MHC-I Molecules by a Dendritic Cell .jpg by Gary E. Kaiser, Ph.D.
Professor of Microbiology, The Community College of Baltimore County, Catonsville Campus
This work is licensed under a Creative Commons Attribution 4.0 International License.
Based on a work at https://cwoer.ccbcmd.edu/science/microbiology/index_gos.html.

Last updated: August, 2019
Please send comments and inquiries to Dr. Gary Kaiser

Fig. 2: Activation of a Macrophage by a TH1 Lymphocyte

Fig. 2: Activation of a Macrophage by a T_H1 Lymphocyte