© 1989 by The Society for Integrative and Comparative Biology
Immunology and Immunoregulation of Parasitic Hematozoan Infections1
Department of Biology, Wake Forest University Winston-Salem, North Carolina 27109
The hematozoan parasites comprise a medically important group of organisms which have received increasing attention in recent years. Malaria, particularly, has garnered significant research effort in regards to the development of sporozoite-specific vaccines. However, initial enthusiasm for an effective vaccine has been dampened as a result of field studies showing the presence of surface epitope-specific antibodies in drugcured and subsequently reinfected patients. Of importance, increasing evidence exists that cell-mediated immune mechanisms may play a central role in protection and pathogenesis in malaria. New evidence to unravel the mechanisms and significance of immunosuppression in leishmaniasis and Chagas' disease continues to implicate a complex circuit involving suppressor macrophages, lymphokine deficiencies, and atypical behavior of T helper cell populations. The African trypanosomes provide the cellular and molecular biologists challenges in understanding the basis and regulation of variant-specific glycoproteins (VSG) and their significance in immunity and pathogenesis. An important recent determination is that there appears to be little or no correlation between expression of a specific VSG and pathogenesis. The present status of research on the hematozoan parasites reestablishes the remarkable evolutionary accomplishments of these organisms to survive in the hostile immune environment of their vertebrate hosts.