Immune system (part 1)

 Immune system

THE IMMUNE SYSTEM

• Molecules, cells, tissues and organs which provide non-specific and specific protection against

• Microorganisms 

• Microbial toxins 

• Tumor cells 

– Crucial to human survival 

ORIGIN OF CELLS OF THE IMMUNE SYSTEM

• Derived from common progenitor cell in bone marrow

– Pluripotent hematopoietic stem cell 

• Progenitor Stem Cells

 – Myeloid lineage 

• Monocyte/macrophage, dendritic cells, PMN’s, mast cells

 • Erythroid : Erythrocytes and Megakaryocytes 

– Lymphoid lineage

 • Small and large lymphocytes

                   Hematopoietic stem cell

GATA transcription factors are a family of transcription factors characterized by their ability to bind to the DNA sequence "GATA“ 

Oct-2 is a octamer transcription factor which is part of the POU family. 

 POU (pronounced 'pow') is a family of proteins that have well-conserved homeodomains. The acronym POU is derived from the names of three transcription factors: 

the Pituitary-specific Pit-1 

the Octamer transcription factor proteins Oct-1 and Oct-2 (octamer sequence is ATGCAAAT)

 the neural Unc-86 transcription factor from Caenorhabditis elegans

CELLS OF INNATE AND ADAPTIVE IMMUNITY

– Myeloid Lineage

 – Referred to as

 • Polymorphonuclear leukocytes (PMN’s)

     – Nuclei are multilobed (2 to 5)

 • Granulocytes 

    – Cytoplasmic granules

– Neutrophil: Principal phagocytic cell of innate immunity

– Eosinophil: Principal defender against parasites 

– Basophil: Functions similar to eosinophils and mast cells 

Neutrophils and macrophages 

• Phagocytes - travel throughout body in pursuit of invading pathogens

• Neutrophils are found in bloodstream ; most abundant phagocyte, normally representing 50% to 60% of circulating leukocytes 

• During acute phase of inflammation, particularly as a result of bacterial infection, neutrophils migrate toward site of inflammation in a process called chemotaxis, and are usually first cells to arrive at scene of infection

 • Macrophages are versatile cells that reside within tissues and produce a wide array of chemicals including enzymes, complement proteins, and regulatory factors such as interleukin 1

 • Macrophages also act as scavengers, ridding body of worn-out cells and other debris, and as antigen-presenting cells that activate adaptive immune system  

Eosinophils 

• Kills Ab-coated parasites through degranulation

• Involved in allergic inflammation 

• A granulocyte

• Double Lobed nucleus 

• Orange granules contain toxic compounds    

Basophils 

• Might be “blood Mast cells’ 

• A cell-killing cells

         – Blue granules contain toxic and inflammatory compounds 

• Important in allergic reactions

CELLS OF INNATE AND ADAPTIVE IMMUNITY

• Myeloid lineage 

         – Monocytes

• Leukocytes with bean shaped or brain-like convoluted nuclei 

• Circulate in blood with half life of 8 hours

• Precursors of tissue macrophages

         – Macrophages

 • Mononuclear phagocytic cells in tissue

 • Derive from blood monocytes

 • Participate in innate and adaptive immunity

CELLS OF INNATE AND ADAPTIVE IMMUNITY

• Myeloid lineage

     – Dendritic cells

        • Cells with dendriform (star shaped) morphology

        • Interdigitating reticular cells (synonym) 

        • Capture and present antigens to T lymphocytes

     – Mast cells 

        • Located in mucous membrane and connective tissue throughout body

        • Major effectors cell in allergy

        • Modulation of initial immune response   

  

to be continue