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Enhanced killing of Blastomyces dermatitidis by gamma interferon-activated murine peripheral blood polymorphonuclear
1Department of Medicine, Santa Clara Valley Medical Center, CA.
Abstract:
Normal peripheral blood polymorphonuclear neutrophils (PB-PMNs), challenged in vitro with yeast form Blastomyces dermatitidis, reduced inoculum colony-forming units of a virulent strain by 37.5 +/- 9.5%. Pre-incubation of PB-PMNs with 10-100,000 U/ml of purified recombinant murine gamma-interferon (IFN) for 1 h prior to challenge with fungi resulted in significant enhancement of PB-PMN fungicidal activity. No direct fungicidal activity by IFN alone was observed. Pretreatment of selected concentrations of IFN shown to have PMN-enhancing activity (100 or 1000 U/ml) with rabbit hyperimmune anti-IFN antiserum for 1 h before addition to PB-PMNs abrogated the enhancement of fungicidal activity. Isolated peripheral blood mononuclear cells failed to kill B. dermatitidis, even when mononuclear cells were present at a concentration ten times greater than that normally used in killing assays, and failed to be activated by IFN. Treatment of unstimulated or IFN-activated PB-PMNs with complement and hybridoma-derived monoclonal antibody specific for PMNs eliminated PB-PMN fungicidal activity. Exogenously added lipopolysaccharide (0.0005-50,000 ng/ml) did not activate PB-PMNs, whether added alone or in conjunction with IFN. The PB-PMN activating capacity of IFN could be destroyed by heat treatment (100 degrees C, 15 min) or by acid treatment with HCl (pH 2). These results demonstrate that recombinant gamma-interferon can stimulate PB-PMNs to kill B. dermatitidis, that the PB-PMN activating moiety is IFN and that PB-PMNs are responsible for fungal killing in this assay system.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Recombinant gamma-interferon (IFN) enhances the ability of normal human polymorphonuclear neutrophils (PB-PMNs) to kill Blastomyces dermatitidis. This study confirms PB-PMNs are responsible for fungal killing, activated by IFN.
Area of Science:
- Immunology
- Microbiology
- Cell Biology
Background:
- Normal peripheral blood polymorphonuclear neutrophils (PB-PMNs) exhibit limited in vitro fungicidal activity against Blastomyces dermatitidis.
- Understanding immune cell activation is crucial for developing strategies against fungal infections.
Purpose of the Study:
- To investigate the effect of recombinant murine gamma-interferon (IFN) on the fungicidal activity of human PB-PMNs against Blastomyces dermatitidis.
- To elucidate the role of PB-PMNs and IFN in the immune response to B. dermatitidis.
Main Methods:
- PB-PMNs were challenged in vitro with yeast form B. dermatitidis.
- PB-PMNs were pre-incubated with varying concentrations of recombinant murine IFN before fungal challenge.
- The role of IFN was confirmed using anti-IFN antiserum, and complement-mediated lysis was used to identify PMNs as the effector cells.
Main Results:
- IFN significantly enhanced the fungicidal activity of PB-PMNs against B. dermatitidis.
- No direct fungicidal effect of IFN alone was observed.
- Anti-IFN antiserum abrogated the enhancing effect of IFN, and complement-mediated lysis eliminated PB-PMN fungicidal activity, confirming IFN's role and PMNs as effector cells.
Conclusions:
- Recombinant gamma-interferon stimulates PB-PMNs to enhance their fungicidal activity against B. dermatitidis.
- The study identifies IFN as the activating moiety and PB-PMNs as the primary effector cells responsible for fungal killing in this assay.