This preview shows pages 1–3. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: Immmunology Problems Topic Overview Isotype Switching T cell help through the CD40/CD40L interaction is required for isotype switching. The FLOW patterns show that expression of CD40 and CD40 L appears normal. Expression of AID is also required for isotype switching. If there is an I region present: The defect could be in CD40 or CD40L: an interaction between them is required to isotype switch. The defect could be an overproduction of IFN-γ which blocks DNA rearrangement (switching). The defect could not be in IL-4 or its receptor since there is transcription of the unrearranged gene. If there is no I region present: then it must be AID protein (if no transcripts are formed and no Ig is present). T Cell If all you know is that T cells are not functioning — or maybe not mounting a secondary response — then a good defect candidate is CD40L. No Antibodies If they are not rearranging, that is the likely cause of no expression. If they are rearranging, there is a defect in something required for surface expression: candidates are the membrane exon of the heavy chain, Ig-α, Ig-β, or surrogate light chain; or proteins required to transport the antibody to the surface. No Rearrangement Frequently caused by lack of RAG enzymes leading to no antibody production and no T cell maturation (arrested at DN stage). CD40/CD40L Needed for isotype switching. IgG1/IgE deficiency A selective decrease in IgG1 and IgE is observed. The most likely expanation is a defect in IL-4 (or IL-4R) or possibly an increase in IFN-γ because these selectively impact these isotypes. Since IgG2 and IgG3 remain essentially unchanged it does not appear to be a general defect such as CD40 or CD40L. Filed Under: Study Guide Tagged With: mimg 185a Immunology Probes Probe Overview Ig DNA Unrearranged DNA shows as a single line. Rearranged DNA shows as a smear. I mRNA When T cell help ( CD40-CD40L) interaction occurs there is DNA rearrangement such that VH is joined to Cε; Iε is removed from the genome and the mRNA no longer contains it. If I mRNA is not excised, but nonfunctioning immunoglobulin is still produced, then cytokine receptors are functioning but CD40/CD40L interaction is askew. Filed Under: Study Guide Tagged With: mimg 185a Immunology Crash Study Guide Topic Overview Adoptive Transfer Type of immunization involving the transfer of “sensitized” cells, serum or other components to a recipient. Hapten-Carrier Hapten-Carrier Hapten Carrier Protein ARS-OVA Azophenylarsonate Ovalbumin DNP-BGG Dinitrophenol Bovine gamma globulin LAC-HGG Phenyllactoside Human gamma globulin NIP-KLH S-nitrophenyl acetic acid Keyhole limpet hemocyanin TNP-BSA Trinitrophenyl Bovine serum albumin Haptens must be bound to carriers to induce a humoral response. The same hapten-carrier conjugate must be used to elicit a secondary response; to generate a secondary response to a hapten bound to a different carrier, the patient must first be immunized against the new carrier. T cells bind carriers; B cells bind haptens. The response of hapten-primed B cells to a hapten-cells bind carriers; B cells bind haptens....
View Full Document
This note was uploaded on 03/08/2011 for the course MIMG 185 taught by Professor Zack during the Spring '06 term at UCLA.
- Spring '06