Immunology

It has been known for the past 85 years that mucosal responses can be stimulated by local presentation of antigen and that the gut immune system is capable of mounting both primary and secondary responses to potentially harmful antigens while avoiding the expression of damaging responses to harmless dietary proteins. How these types of responses are induced and regulated remains unclear. In the gut attention has for some time been focused on Peyer's patches (PP) due to evidence that they play a vital role in the induction of humoral and cellular responses. Moreover, it has been established that MHC class II molecules are found in the gut mucosa on a variety of cell types outside PP, namely the lamina propria (LP). Fed antigens have also been detected in the LP and studies have shown that LP cells can stimulate allogeneic mixed lymphocyte responses and are capable of presenting soluble protein antigen to naïve T cells. This article reviews the present understanding of the possible roles of PP and LP in intestinal immunity in terms of induction, regulation, surveillance of immune responses and the antigen presenting cell types involved.     

Comparative Immunology

Comparative Immunology includes an evolutionary approach toimmunity revealing the immune system as widespread and necessaryfor survival. Although many immunology textbooks and coursesare often oriented solely toward medicine orallied professions,comparative immunology is a unique beginning for advanced undergraduatestudents of biology, zoology, and immunology. A more biologicapproach to immune competence causes mammalian immunologiststo view comparative immunology as an introduction to numerousectothermic vertebrates and invertebrates. Such exotic animalsare sources of meaningful facts important for anyone viewingsignificant breakthroughs in immunology in phylogenetic perspective.Animals preserve their unique individuality by distinguishingbetween self and non-self to protect against infection and possibleextinction. The earliest beginnings of immune reactions arebest exemplified among the invertebrates by recognition, phagocytosis,graft rejection accompanied by specificity and weak memory,and the induction of agglutinins and lectins. Although vertebratesshare these same responses, the main differences include moreextensive evidence of specificity and memory and the uniquecapacity to synthesize immunoglobulins. Acknowledging the problemof recognition as the common basis for the immune response,certain members of the Ig superfamily, notably Thy-1 and ß₂-microglobulin,will help our attempts to define evolutionary pressures thatcaused the development of immunity.