Antibody-coated pathogens are recognized by effector cells through Fc receptors, making option (B) the correct answer.

Option Analysis

(A) CD4 Receptor

CD4 receptors are found on helper T cells and bind to MHC class II molecules on antigen-presenting cells. They play a key role in T cell activation but do not recognize antibody-coated pathogens.

(B) Fc Receptor

Fc receptors on effector cells like macrophages, neutrophils, and NK cells bind the Fc portion of antibodies coating pathogens. This triggers phagocytosis, antibody-dependent cellular cytotoxicity (ADCC), or lysosomal degradation.

(C) CD8 Receptor

CD8 receptors are on cytotoxic T cells and interact with MHC class I for direct killing of infected cells. They do not bind antibodies or recognize opsonized pathogens.​

(D) IFN Gamma Receptor

IFN-gamma receptors on various cells respond to the cytokine IFN-gamma to activate macrophages and enhance antigen presentation. They have no role in direct recognition of antibody-coated pathogens.​

Introduction to Antibody Coated Pathogens Fc Receptor

In immunology, antibody coated pathogens are recognized by effector cells through Fc receptor, a critical mechanism for opsonization and clearance. This process is key for competitive exams like GATE Life Sciences, where questions test recognition of antibody-coated pathogens by effector cells.

How Fc Receptors Enable Pathogen Recognition

Effector cells such as macrophages and neutrophils use Fc receptors to bind the Fc region of IgG antibodies on pathogens. This binding activates phagocytosis, directing coated microbes to lysosomes for destruction. Studies show Fc receptor engagement alters intracellular trafficking, preventing pathogen replication.

Why Not Other Receptors?

• CD4 Receptor: Limited to T helper cell-MHC II interactions; irrelevant for antibody binding.​

• CD8 Receptor: Exclusive to cytotoxic T cell function against virally infected cells.​

• IFN Gamma Receptor: Mediates cytokine signaling for macrophage activation, not direct opsonin recognition.​