STRUCTURAL AND FUNCTIONAL ALTERATIONS OF THE COMPLEMENT SYSTEM IN CHRONIC LYMPHOCYTIC LEUKEMIA PATIENTS
(Abstract release date: 05/19/16)
EHA Library. Michelis R. 06/09/16; 134679; PB1779
Dr. Regina Michelis
Contributions
Contributions
Abstract
Abstract: PB1779
Type: Publication Only
Background
Chronic lymphocytic leukemia (CLL) is the most common adult leukemia in the western world, accounting for 30% of all leukemias. The therapeutic approach in CLL includes chemotherapeutic regimens of purine analogues and therapeutic monoclonal antibodies. The immunotherapeutic approach triggers immune responses against the leukemic B-cells that synergize with cytotoxic chemotherapeutic agents. The therapeutic monoclonal antibodies mediate anti-tumor effects through complement-mediated cytotoxicity (CDC), antibody-dependent cell-mediated cytotoxicity (ADCC), and phagocytosis. The efficacy of the CDC thus depends on the expression level of the targeted antigen on B-cells, the integrity of apoptotic cascades within tumor cells, the functional capacity of effector cells, and the availability and activity of the complement system.
Aims
To study structural and functional characteristics of key complement components in untreated CLL patients, in order to develop a marker which will assist in identifying patients who are likely to be less responsive to future immunotherapy treatment.
Methods
Blood samples were collected from 13 untreated CLL patients and 8 healthy controls (HC). Clinical biochemical and haematological parameters, as well as CLL staging were recorded. Three key complement components, C3, C4 and C5 were studied by Western blot analysis. The activity of the complement system before and after activation with Zymosan or aggregated IgG was followed by the levels of C5b-9, the terminal product of complement activation, using ELISA. The link between levels of complement activity and complement isoforms, as revealed by Western analysis, was studied.
Results
The Western analysis results indicate differences in the pattern of C5 and C4 in CLL patients compared to HC subjects. Specifically, the C5 complex, which exists as a single band in HC, appeared in CLL patients as a clear double-band. This alteration was observed in >50% of the patients. Western analysis did not indicate clear differences in C3 pattern in the patients. Activity analysis revealed higher basal levels of C5b-9 in the CLL patients (compared with HC), that were particularly high in the patients presenting altered pattern of C5. Maximal activation, achieved by Zymosan or aggregated IgG, appeared to be inversely correlated with basal activation levels.
Conclusion
These preliminary data demonstrate a possible link between the activation potential of the complement system in CLL patients and alterations in the complex structure of C5. The exact mechanism by which 'modified' C5 distracts the complement activity needs further clarification. Yet, the appearance of 'modified' C5 in CLL patients with disturbed complement activity bears the potential to develop a marker which will assist in identifying patients who are likely to be less responsive to future immunotherapy treatment due to compromised CDC. Development of such a marker may assist clinicians in refining and personalizing the immunotherapeutic approach, improving CDC and consequently the therapy results.
Session topic: E-poster
Keyword(s): Chronic lymphocytic leukemia, Complement
Type: Publication Only
Background
Chronic lymphocytic leukemia (CLL) is the most common adult leukemia in the western world, accounting for 30% of all leukemias. The therapeutic approach in CLL includes chemotherapeutic regimens of purine analogues and therapeutic monoclonal antibodies. The immunotherapeutic approach triggers immune responses against the leukemic B-cells that synergize with cytotoxic chemotherapeutic agents. The therapeutic monoclonal antibodies mediate anti-tumor effects through complement-mediated cytotoxicity (CDC), antibody-dependent cell-mediated cytotoxicity (ADCC), and phagocytosis. The efficacy of the CDC thus depends on the expression level of the targeted antigen on B-cells, the integrity of apoptotic cascades within tumor cells, the functional capacity of effector cells, and the availability and activity of the complement system.
Aims
To study structural and functional characteristics of key complement components in untreated CLL patients, in order to develop a marker which will assist in identifying patients who are likely to be less responsive to future immunotherapy treatment.
Methods
Blood samples were collected from 13 untreated CLL patients and 8 healthy controls (HC). Clinical biochemical and haematological parameters, as well as CLL staging were recorded. Three key complement components, C3, C4 and C5 were studied by Western blot analysis. The activity of the complement system before and after activation with Zymosan or aggregated IgG was followed by the levels of C5b-9, the terminal product of complement activation, using ELISA. The link between levels of complement activity and complement isoforms, as revealed by Western analysis, was studied.
Results
The Western analysis results indicate differences in the pattern of C5 and C4 in CLL patients compared to HC subjects. Specifically, the C5 complex, which exists as a single band in HC, appeared in CLL patients as a clear double-band. This alteration was observed in >50% of the patients. Western analysis did not indicate clear differences in C3 pattern in the patients. Activity analysis revealed higher basal levels of C5b-9 in the CLL patients (compared with HC), that were particularly high in the patients presenting altered pattern of C5. Maximal activation, achieved by Zymosan or aggregated IgG, appeared to be inversely correlated with basal activation levels.
Conclusion
These preliminary data demonstrate a possible link between the activation potential of the complement system in CLL patients and alterations in the complex structure of C5. The exact mechanism by which 'modified' C5 distracts the complement activity needs further clarification. Yet, the appearance of 'modified' C5 in CLL patients with disturbed complement activity bears the potential to develop a marker which will assist in identifying patients who are likely to be less responsive to future immunotherapy treatment due to compromised CDC. Development of such a marker may assist clinicians in refining and personalizing the immunotherapeutic approach, improving CDC and consequently the therapy results.
Session topic: E-poster
Keyword(s): Chronic lymphocytic leukemia, Complement
Abstract: PB1779
Type: Publication Only
Background
Chronic lymphocytic leukemia (CLL) is the most common adult leukemia in the western world, accounting for 30% of all leukemias. The therapeutic approach in CLL includes chemotherapeutic regimens of purine analogues and therapeutic monoclonal antibodies. The immunotherapeutic approach triggers immune responses against the leukemic B-cells that synergize with cytotoxic chemotherapeutic agents. The therapeutic monoclonal antibodies mediate anti-tumor effects through complement-mediated cytotoxicity (CDC), antibody-dependent cell-mediated cytotoxicity (ADCC), and phagocytosis. The efficacy of the CDC thus depends on the expression level of the targeted antigen on B-cells, the integrity of apoptotic cascades within tumor cells, the functional capacity of effector cells, and the availability and activity of the complement system.
Aims
To study structural and functional characteristics of key complement components in untreated CLL patients, in order to develop a marker which will assist in identifying patients who are likely to be less responsive to future immunotherapy treatment.
Methods
Blood samples were collected from 13 untreated CLL patients and 8 healthy controls (HC). Clinical biochemical and haematological parameters, as well as CLL staging were recorded. Three key complement components, C3, C4 and C5 were studied by Western blot analysis. The activity of the complement system before and after activation with Zymosan or aggregated IgG was followed by the levels of C5b-9, the terminal product of complement activation, using ELISA. The link between levels of complement activity and complement isoforms, as revealed by Western analysis, was studied.
Results
The Western analysis results indicate differences in the pattern of C5 and C4 in CLL patients compared to HC subjects. Specifically, the C5 complex, which exists as a single band in HC, appeared in CLL patients as a clear double-band. This alteration was observed in >50% of the patients. Western analysis did not indicate clear differences in C3 pattern in the patients. Activity analysis revealed higher basal levels of C5b-9 in the CLL patients (compared with HC), that were particularly high in the patients presenting altered pattern of C5. Maximal activation, achieved by Zymosan or aggregated IgG, appeared to be inversely correlated with basal activation levels.
Conclusion
These preliminary data demonstrate a possible link between the activation potential of the complement system in CLL patients and alterations in the complex structure of C5. The exact mechanism by which 'modified' C5 distracts the complement activity needs further clarification. Yet, the appearance of 'modified' C5 in CLL patients with disturbed complement activity bears the potential to develop a marker which will assist in identifying patients who are likely to be less responsive to future immunotherapy treatment due to compromised CDC. Development of such a marker may assist clinicians in refining and personalizing the immunotherapeutic approach, improving CDC and consequently the therapy results.
Session topic: E-poster
Keyword(s): Chronic lymphocytic leukemia, Complement
Type: Publication Only
Background
Chronic lymphocytic leukemia (CLL) is the most common adult leukemia in the western world, accounting for 30% of all leukemias. The therapeutic approach in CLL includes chemotherapeutic regimens of purine analogues and therapeutic monoclonal antibodies. The immunotherapeutic approach triggers immune responses against the leukemic B-cells that synergize with cytotoxic chemotherapeutic agents. The therapeutic monoclonal antibodies mediate anti-tumor effects through complement-mediated cytotoxicity (CDC), antibody-dependent cell-mediated cytotoxicity (ADCC), and phagocytosis. The efficacy of the CDC thus depends on the expression level of the targeted antigen on B-cells, the integrity of apoptotic cascades within tumor cells, the functional capacity of effector cells, and the availability and activity of the complement system.
Aims
To study structural and functional characteristics of key complement components in untreated CLL patients, in order to develop a marker which will assist in identifying patients who are likely to be less responsive to future immunotherapy treatment.
Methods
Blood samples were collected from 13 untreated CLL patients and 8 healthy controls (HC). Clinical biochemical and haematological parameters, as well as CLL staging were recorded. Three key complement components, C3, C4 and C5 were studied by Western blot analysis. The activity of the complement system before and after activation with Zymosan or aggregated IgG was followed by the levels of C5b-9, the terminal product of complement activation, using ELISA. The link between levels of complement activity and complement isoforms, as revealed by Western analysis, was studied.
Results
The Western analysis results indicate differences in the pattern of C5 and C4 in CLL patients compared to HC subjects. Specifically, the C5 complex, which exists as a single band in HC, appeared in CLL patients as a clear double-band. This alteration was observed in >50% of the patients. Western analysis did not indicate clear differences in C3 pattern in the patients. Activity analysis revealed higher basal levels of C5b-9 in the CLL patients (compared with HC), that were particularly high in the patients presenting altered pattern of C5. Maximal activation, achieved by Zymosan or aggregated IgG, appeared to be inversely correlated with basal activation levels.
Conclusion
These preliminary data demonstrate a possible link between the activation potential of the complement system in CLL patients and alterations in the complex structure of C5. The exact mechanism by which 'modified' C5 distracts the complement activity needs further clarification. Yet, the appearance of 'modified' C5 in CLL patients with disturbed complement activity bears the potential to develop a marker which will assist in identifying patients who are likely to be less responsive to future immunotherapy treatment due to compromised CDC. Development of such a marker may assist clinicians in refining and personalizing the immunotherapeutic approach, improving CDC and consequently the therapy results.
Session topic: E-poster
Keyword(s): Chronic lymphocytic leukemia, Complement
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