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Updated: Oct 23, 2026

Visualizing Antigen Specific CD4+ T Cells using MHC Class II Tetramers
Published on: March 5, 2009
Antigen form influences induction and frequency of influenza-specific class I and class II MHC-restricted cytolytic T
L A Morrison1, V L Braciale, T J Braciale
1Department of Pathology, Washington University School of Medicine, St. Louis, MO 63110.
The induction of class I and class II MHC-restricted CTL in response to different forms of A/JAP/57 influenza virus was compared. Splenocytes removed from influenza-immune BALB/c mice and stimulated in vitro with infected syngeneic splenocytes are mainly CD8+ (Lyt-2+) and specifically lyse infected Ia- and Ia+ target cells. To a lesser extent they also lyse non-infectious virus-pulsed Ia+ but not Ia- target cells. In contrast, syngeneic stimulators pulsed with non-infectious virus (exogenous Ag) induce effector T cells that specifically lyse both infected and non-infectious virus-pulsed Ia+ target cells. The cells present in this heterogeneous culture predominantly express the CD4 (L3T4) cell surface marker. Frequency analysis by limiting dilution of splenocytes derived directly from influenza-immune mice revealed a similar pattern of precursor induction: In vitro stimulation with infected splenocytes yielded primarily class I MHC-restricted CTL, whereas stimulation with non-infectious virus reciprocally induced primarily class II MHC-restricted CTL. Thus, the Ag form and consequently the intracellular route of viral Ag presentation profoundly influence the MHC restriction of CTL precursors induced.
The induction of class I and class II MHC-restricted CTL in response to different forms of A/JAP/57 influenza virus was compared. Splenocytes removed from influenza-immune BALB/c mice and stimulated in vitro with infected syngeneic splenocytes are mainly CD8+ (Lyt-2+) and specifically lyse infected Ia- and Ia+ target cells. To a lesser extent they also lyse non-infectious virus-pulsed Ia+ but not Ia- target cells. In contrast, syngeneic stimulators pulsed with non-infectious virus (exogenous Ag) induce effector T cells that specifically lyse both infected and non-infectious virus-pulsed Ia+ target cells. The cells present in this heterogeneous culture predominantly express the CD4 (L3T4) cell surface marker. Frequency analysis by limiting dilution of splenocytes derived directly from influenza-immune mice revealed a similar pattern of precursor induction: In vitro stimulation with infected splenocytes yielded primarily class I MHC-restricted CTL, whereas stimulation with non-infectious virus reciprocally induced primarily class II MHC-restricted CTL. Thus, the Ag form and consequently the intracellular route of viral Ag presentation profoundly influence the MHC restriction of CTL precursors induced.
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