4.2 CÉLULAS Y MECANISMOS DE INMUNIDAD INNATA.

Innate Immunity and Phagocytosis

This section delves into the mechanisms of phagocytosis within innate immunity, exploring the receptors involved and the processes that lead to pathogen destruction.

Receptors Involved in Phagocytosis

• Phagocytes have two main groups of receptors for phagocytosis:

• Pattern recognition receptors (PRRs) that recognize pathogen-associated patterns (PAMPs), such as the mannose receptor.

• Receptors for immune system proteins known as opsonins, including immunoglobulins and complement system proteins.

Process of Phagocytosis

• Phagocytosis initiates with pathogen recognition, leading to engulfment in a phagosome followed by fusion with primary lysosomes containing hydrolytic enzymes.

• Hydrolytic enzymes in lysosomes degrade pathogens' components like carbohydrates, lipopolysaccharides, and proteins.

• Enzymes like NADPH oxidase and inducible nitric oxide synthetase produce reactive oxygen species (ROS) crucial for pathogen degradation.

Phagocytosis Mechanisms in Action

This section illustrates how phagocytes function during infection through the process of phagocytosis.

Phagocyte Functionality During Infection

• Upon encountering bacteria, phagocytes utilize receptors like mannose receptors to initiate phagocytosis by recognizing specific bacterial surface components.

• The engulfed bacteria are degraded within the phagosome through fusion with primary lysosomes containing hydrolytic enzymes.

• Efficiency of phagocytosis increases when complement receptors participate alongside immunoglobulin and mannose receptors.

Impact of Enzyme Failure on Phagocytosis

This segment explores the consequences of enzyme failure, particularly focusing on NADPH oxidase deficiency.

Consequences of Enzyme Failure

• Defects in NADPH oxidase can lead to ineffective bacterial destruction post-phagocytosis, resulting in bacterial persistence within macrophages.

Detailed Overview of the Transcript

In this section, the speaker discusses a case study involving an infected area in a patient with chronic granulomatous disease due to defects in NADPH oxidase protein subunits. The implications of these defects on phagocytosis and clinical outcomes are highlighted.

Patient Case Study and Immunodeficiency

• The speaker presents an infected area in a patient with chronic granulomatous disease that requires surgical drainage.

• Patients suffering from chronic granulomatous disease exhibit immunodeficiency caused by defects in the protein subunits of NADPH oxidase.

Defects in NADPH Oxidase Protein Subunits

• Chronic granulomatous disease results from defects in the protein subunits of NADPH oxidase, leading to impaired immune function.

• The inheritance pattern of these defects can be sex-linked or autosomal recessive based on the defective protein involved.

Implications and Clinical Relevance

• Two main groups of innate cell receptors play crucial roles in phagocytosis, impacting pathogen clearance.

• Understanding how phagocytosis proceeds and the enzymatic actions post-phagocytosis is essential for comprehending immune responses.

• Clinical implications arise from defects in NADPH oxidase, affecting immune function and pathogen clearance mechanisms.

Key Questions for Understanding

• What types of receptors promote phagocytosis within innate immune cells?