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Sources of antibody-dependent cellular cytotoxicity deficiency in young pig leukocytes
1Department of Veterinary Pathobiology, College of Veterinary Medicine, University of Illinois, Urbana-Champaign 61801.
Insights
Young pigs exhibit lower antibody-dependent cellular cytotoxicity (ADCC) due to reduced antibody binding to Fc receptors on neutrophils. This impacts their immune response to infections like pseudorabies virus.
Area of Science:
- Veterinary Immunology
- Infectious Disease Immunology
Background:
- Young pigs are more susceptible to fatal pseudorabies virus infections.
- Antibody-dependent cellular cytotoxicity (ADCC) plays a crucial role in controlling viral infections.
- Lower ADCC activity in young pigs compared to adults suggests an underlying immune deficiency.
Purpose of the Study:
- To investigate the reasons for the reduced ADCC activity in young pigs against pseudorabies virus-infected cells.
- To identify the specific immune cell populations or factors responsible for this deficiency.
Main Methods:
- Comparison of ADCC activity in peripheral blood leukocytes (PBLs) from young and adult pigs.
- Analysis of polymorphonuclear leukocyte (PMN) percentages and enrichment.
- Assessment of suppressor cell activity.
- Evaluation of effector cell binding to antibody-sensitized targets and Fc receptor affinity.
Main Results:
- The percentage of PMNs did not correlate with ADCC deficiency.
- Enriching PMNs did not resolve the activity difference between age groups.
- No suppressor cells or factors were identified as the cause.
- The primary cause identified was the decreased ability of young pig effector cells to bind antibody-sensitized targets.
- This binding defect was linked to reduced antibody interaction with high-affinity Fc receptors on young neutrophils.
Conclusions:
- The ADCC deficiency in young pigs is not due to PMN numbers or suppressor cells.
- The deficiency stems from impaired effector cell binding to antibody-coated targets.
- Reduced antibody binding to high-affinity Fc receptors on neutrophils is the key factor contributing to lower ADCC in young pigs.
Abstract:
Antibody-dependent cellular cytotoxicity (ADCC) activity against pseudorabies virus-infected target cells has been found to be lower in young pig peripheral blood leukocytes (PBLs) than in adults. Experiments were designed to investigate the reason(s) for low activity in the young, which are more at risk of fatal infection than adults. The percentage of polymorphonuclear leukocytes (PMNs), the major ADCC effector cell, in the whole leukocyte population did not have a bearing on the deficiency. Enrichment for PMNs did not alleviate differences in activity between young and adult pigs. Additionally, no suppressor cell(s) or factor(s) could be demonstrated to account for the ADCC deficiency. The source of the ADCC deficiency in the young was found to be related to the decreased ability of young pig effector cells to bind antibody-sensitized targets. This deficiency relative to adults was associated with decreased antibody binding to high affinity Fc receptors on young pig neutrophils.