concanamycin-a and Herpes-Simplex

The present study was undertaken to clarify the mechanisms of cytotoxicity mediated by virus-specific human CD4+ CTLs using the lymphocytes of family members with a Fas gene mutation. CD4+ CTL bulk lines and clones directed against HSV-infected cells were established from lymphocytes of a patient with a homozygous Fas gene mutation and of the patient's mother. HSV-specific CD4+ CTLs generated from lymphocytes of the patient and her mother exerted cytotoxicity against HSV-infected cells from the patient (Fas-/-) and from her mother (Fas+/-) to almost the same degree in an HLA class II-restricted manner. mRNAs for the major mediators of CTL cytotoxicity, Fas ligand, perforin, and granzyme B, were detected in these CD4+ CTLs using the RT-PCR and flow cytometry. The cytotoxicity of the HSV-specific CD4+ CTLs appeared to be Ca2+-dependent and was almost completely inhibited by concanamycin A, a potent inhibitor of the perforin-based cytotoxic pathway. Although the Fas/Fas ligand system has been reported to be the most important mechanism for CD4+ CTL-mediated cytotoxicity in the murine system, the present findings strongly suggest that granule exocytosis, not the Fas/Fas ligand system, is the main pathway for the cytotoxicity mediated by HSV-specific human CD4+ CTLs.

Topics: Anti-Bacterial Agents; Calcium; CD4-Positive T-Lymphocytes; Clone Cells; Consanguinity; Cytotoxicity, Immunologic; DNA Fragmentation; Fas Ligand Protein; fas Receptor; Female; Granzymes; Herpes Simplex; Heterozygote; Histocompatibility Testing; Homozygote; Humans; Macrolides; Membrane Glycoproteins; Pedigree; Perforin; Point Mutation; Pore Forming Cytotoxic Proteins; Serine Endopeptidases; T-Lymphocytes, Cytotoxic