comparative / vetinary immunology

comparative immunology

investigates major differences in the immune system between different organisms

usually those that are distantly related

• fish vs. marsupials vs. mammals

why study comparative immunology

investigate variation in immune mechanisms

• aspects not observed in certain species etc → finding aspects not observed in humans can help us better understand us and improve us?

• develop model systems for studying immunity

investigation immune system evolution

• study taxa with interesting position in phylogenetic tree → marsupials and monotremes, special differences

marsupials and monotremes

prototherians → monotremes → egg laying mammals (most primitive branch)

therians → marsupials → pouch / live young + placentals (eutherians)

eutherians → type of therian, mammals + humans, long gestation

monotreme evolution

~150 MY of evolution between monotremes, marsupials and eutherian mammels means these mammals are ideal for comparative immunology studies

comparative immunology involves studying

1. anatomical differences - lymphoid tissues

2. functional differences - presence/activtiy of immune cell populations

3. molecular - immunogenetics

anatomical differences

early 1900s = many studies on marsupials and monotreme tissues

primary + secondary tissues = bone marrow, spleen, LNs, MALT

similar structures and complexity to humans

differences = THYMUS + DEVELOPMENT

thymus

polyprotodont marsupials (multiple teath, opossum)

• located: thorax

• t lymphocyte maturation site

• partially functioning

• involutes with age

diprotodont marsupials (two incisors, wallaby)

• located: cervial + thoracic regions (near clavicle?)

• t lymphocyte mauration site

• partially functioning

• invilutes with age

eutherians

• in thorax (between lungs)

• t lymphocyte maturation

• fully functional at birth

• involvution as age