SOLUTIONS TO EXERCISES, LESSON 4
Immunogenetics is the study of processes involved in the immune response that
may have a genetic basis. These processes include the factors that control the
immune response of the host and the transmission of antigenic specificities from
generation to generation.
The first major area of immunogenetics is concerned with the genetic regulation
and control of the immune system itself. Interruption or alterations of
developmental sequences may lead to immunodeficiency disorders, autoimmune
disorders, and perhaps malignancies.
The second major area of immunogenetics, the one with the broadest application,
is the use of antibodies and sensitized immune cells, products of the immune
system, as probes to detect and characterize various antigens that may show
The major histocompatibility complex (MHC) is the region of a specific
chromosome that controls histocompatibility. The term histocompatibility refers
to the presence of certain antigens which mean that the host of an organ or tissue
graft will not reject the graft. In humans, the MHC is called the HLA complex,
which refers to "human leukocyte antigens." Histocompatibility is a relationship of
donor and host based upon the presence of compatible HLA antigens.
The histocompatibility-linked Ir genes play an important role but compose only a
part of the immune system. Certain Ir genes may code for cellular receptors for
antigen and others may control mediator secretion. The system controls not only
have the ability to respond to antigens but also to control the level and duration of
The HLA complex is a region on chromosome 6 that codes for three functionally
different proteins: those that regulate the immune response, those that determine
the acceptance or rejection of transplanted tissues between individuals within that
species, and those that are a part of the complement system (Figure 4-1). The
MHC of mice has provided information for the understanding of the human MHC.
A letter after HLA, such as HLA-D, refers to a gene locus.