The Immune System Marie Černá

Immune system belongs to basic homeostatic mechanisms of organism Its function is maintaining the integrity of organism by recognition of harmful from harmless, and by this way it protects organism against injurious matter of external and internal origin.

Immune system An antigen is any substance: biological / chemical, natural / artificial, self / nonself that elicits an immune response.

Organs of immune system Cellular components Humoral components

Leucocytes (white cells) the defense of the organism / mm 3 = / l size ≥10 µm in diameter agranulocytes (lymphoid cells) 30% lymphocytes (upper slide) monocytes (lower slide) granulocytes (presence of granules in the cytoplasm) 70% granules have a different affinity towards neutral, acid or basic stains and give the cytoplasm different colors. neutrophils eosinophils (or acidophils) basophils

Monocytes 3-8 % of all leukocytes the biggest leukocytes: µm Their nucleus is a great reniform or horseshoe-shaped. The cytoplasm is transparent, but with an appearance of "ground glass" Monocytes are the precursors of macrophages. After attaining maturity in the bone marrow, enter the blood circulation where they stay for hours. Then they migrate into the connective tissue.

Neutrophils % of all leukocytes Their nucleus is divided into lobes connected by a fine nuclear strand. The cytoplasm is transparent because its granules are small, pink colored. Neutrophils are very active in phagocyting bacteria => are present in large amount in the pus of wounds.

Eosinophils 3-5 % of all leukocytes Their nucleus is bi-lobed (glasses- like shape). The cytoplasm is full of pink- orange colored granules. Eosinophils attack parasites and phagocyte antigen-antibody complexes.

Lymphocytes % of all leukocytes Their nucleus is round and large in comparison to the cell and it occupies most of it. The cytoplasm is transparent. Lymphocytes are cells which, besides being present in the blood, populate the lymphoid tissues and organs too, as well as the lymph circulating in the lymphatic vessel.

Basophils % of all leukocytes Their nucleus is bi- or tri-lobed. The cytoplasm is very rich in dark purple colored granules. Basophils secrete anti-coagulant and vasodilatory substances as histamines and serotonin => mediate the hypersensitivity reaction.

Immunity Innate immunity –First line – integrity of the skin and the mucosa –Second line – nonspecific defense itself - cellular components - humoral components Acquired immunity - cellular components - humoral components

Innate immunity First line – integrity of the skin and the mucosa – defense mechanisms mechanical (movement of cilia) chemical (fatty acids, pH 3-5, lysozyme) microbial (normal microbes)

Innate immunity Second line – nonspecific defense itself - cellular components phagocytic cells natural killer (NK) cells - humoral components complement system interferons

Acquired immunity Specific defense only in vertebrates - cellular components T - lymphocytes B - lymphocytes - humoral components antibodies produced by B - lymphocytes Induction of immunological memory

Literature Biology, eighth edition, Campbell, Reece Unit seven: Animal Form and Function Chapter 43: The Immune System Pages 930 – 953