role of phagocytes in innate/nonspecific immunity

innate: dont remember specific types of pathogen, responds generally

immune system fights proteins, viruses, bacteria, parasites, fungus (pathogens) and keeps them out.

First line - keep pathogens out

• skin

  • oils in skin

• mucus membranes

• stomach acid

Second line

• inflammatory response (bringing fluid and fighters to the fight)

• phagocytes

Phagocytes: cells that can eat up foreigh particles

• has receptors that respond to “bad things”

• once they connect to the pathogen, the phagocytes will wrap around and engulf pathogen

• the pathogen is going to be inside the phagocyte, membranes merge. pathogen in its own vesicle (phagosome)

• vesicles with lysosymes and other things, it will dump contents into phagosome and digest it.

• pathogen gets broken up into proteins. phagocytes will take peptide chains and attatch them to other protein called a major histocompatibility complex type ii and presemt it onto its membrane (antigen presenting chain)

  • antigen: peptide chain that can trigger immune response

• specific parts of immune system can recognize the foreigh thing and activate

Neutrophils - fast and abundant

macrophages

dendritic cells (not related to nervous system, best activators of specific immune system)

Immune system broken into nonspecific and specific.

Nonspecific:

1. barriers

2. inflammatory response

3. phagocytes (leukocytes)

Specific:

• main actors are lymphocytes (leukocyte type)

  • B-lymphocytes (produced in bone marrow)

  • T-lymphocytes (start off in bone marrow, but mature in thymus)

Humoral response: B-lymphocytes. responds to humoral fluids of your body.

Cell mediated response: T-lymphocytes

Humoral response

B-Lymphocytes: have proteins on their surface called membrane bound antibodies/immunoglobulins. each b-cell has one type of antibody on it. they have variable portions that differ from b-cell to b-cell.

• in hematopoesis, re-shuffling of dna that leads to variable portions

eventually one B-cell will have the correct variable portion for any pathogen.

• epitope: a specific region on the surface of an antigen that is recognized by the immune system, specifically by antibodies or T-cell receptors. It's the part of an antigen that an antibody binds to, triggering an immune response. Think of it as a specific "docking site" on a larger molecule

• bind to new pathogen → activated → start cloning itself → differentiate

Memory cells: b cells that stay around for a long time with a pefffect variable portion for a certain pathogen

effector cells: b cells turn into plasma cells sthat create antibodies uniquely able to bind to new pathogen

opsomization: tagging pathogens to make it easier for phagoccytes to digest.

major histocompatability complexes (MHC):

MHC class II are relevant to phagocytes or macrophages or dendritic cells.

For B-Cells:

B cell with membrane bound antibodies has a bacteria binds to it. this starts the activation process. the bacteria gets engulfed by the b-cell. the b-cell proliferates into memory and plasma b cells. plasma b cells start producing antibodies. the b cell also breaks up the bacteria and attatches it to MHC II proteins and present the antigen.

professional antigen presenting cells: Professional antigen presenting cells (APCs) are specialized immune cells that play a crucial role in activating the adaptive immune response by presenting antigens to T cells. The main types of professional APCs are dendritic cells, macrophages, and B cells. They are distinguished by their ability to express MHC class II molecules and costimulatory molecules, which are essential for activating naive T cells.

Adaptive immune system

• humoral: fluids in the body

  • B cells (generate antibodies which attatch to pathogens and disables them)

    • Memory

    • Effector

• cell mediated

  • T cells (mature in thymus)

    • Helper

    • Cytotoxic: attack cells that have been infiltrated

Helper T Cells:

The T cell “raises the alarm:. has t-cell receptors on it that bond to MHC II complexes. T cell receptors have different variable portions. then, it becomes activated. when activated, they proliferate and they differentiate into effector helper t cells and memory helper t cells. memory t cells have the both t cell receptor as the parent. memory helper t cells last longer. the effector t cell raises the alarm. it responds to a specific pathogen and releases cytokines. cytokines trigger other lymphatic or immune cells. effector T cells also binds to MHC II complexes on b cells that activate the B cell.

naive helper t cell: cells that are non memory, non effector, and have never activated or never had anything bonded to it.