James Goding; Week 12 MED1011; Pathology
Passive immunity is transfer of immune serum (antibodies), only lasts a few months because there is no future synthesis from antigen exposure. Antigen exposure drives clonal expansion, generation of memory and antibody synthesis. Serum sickness can occur from immune responses to animal antigens (arthritis, rash, fever, kidney damage), anaphylaxis can occur from IgE antibodies. Hyper-immune gamma globulin is used to treat hepatitis, is of human origin.
Immune deficiency can be congenital, acquired or iatrogenic. DiGeorge syndrome is lack of thymus. Severe combined immune deficiency is combined lack of T and B cells, has no antibody production and can have several causes e.g. mutation. Bone marrow transplant can be curative or can give passive immunity every few months. Stem cells can be transfected with correct genes and replaced into the body but these can become oncogenic. Acquired immune deficiency can be from drugs, bone marrow failure from leukaemia, HIV.
Progression to AIDS takes several years for CD4 count to drop enough. HIV requires CD4 and CCR5 (a chemokine receptor) to enter cells. Integrase integrates transcribed double stranded DNA into host chromosomes. mRNA is transcribed from this and is then translated into proteins. Protease cleaves proteins to make them functional. Reverse transcriptase is error prone so HIV mutates rapidly.