MLPAO Immunology and Serology Flashcards
7 cards from real MLPAO practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 MLPAO Immunology and Serology flashcards as text
In a Western blot (immunoblot), what is the purpose of the electrophoresis step?
Answer: To separate proteins by molecular weight before antibody probing
Electrophoresis separates denatured proteins by molecular weight in a gel matrix before transfer to membrane, allowing identification of specific proteins by size when probed with antibodies.
Which serological test is based on the principle that patient antibodies, if present, will prevent complement-mediated lysis of sensitized red blood cells?
Answer: Complement fixation test
The complement fixation test measures whether patient antibodies bind antigen and 'fix' complement, thereby preventing it from lysing the indicator system of antibody-sensitized sheep red blood cells.
ANA (antinuclear antibody) testing by indirect immunofluorescence using HEp-2 cells: a homogeneous staining pattern is most commonly associated with antibodies to:
Answer: Double-stranded DNA or histones
A homogeneous (diffuse) ANA pattern on HEp-2 cells results from antibodies to double-stranded DNA or histones, and is commonly associated with systemic lupus erythematosus.
The MHC class II molecules present antigen to which subset of T lymphocytes?
Answer: CD4+ helper T cells
MHC class II molecules on antigen-presenting cells present exogenous peptide antigens to CD4+ helper T cells via the CD4 co-receptor, initiating the adaptive immune response.
Which serological marker is the first to appear after hepatitis B infection and indicates active viral replication?
Answer: HBsAg (hepatitis B surface antigen)
HBsAg is the first serological marker to appear after HBV infection, detected before symptoms and before antibody development, indicating active hepatitis B virus infection.
In latex agglutination tests, patient antibodies cause visible clumping because:
Answer: Latex beads coated with antigen cross-link with specific antibodies
Antigen-coated latex beads agglutinate when specific patient antibodies bridge multiple beads simultaneously, forming visible aggregates that indicate a positive result.
A four-fold or greater rise in antibody titer between acute and convalescent serum samples is considered diagnostically significant because it:
Answer: Indicates a current or recent active infection rather than past exposure
A four-fold rise in titer between paired acute and convalescent samples provides strong evidence of active infection, distinguishing it from pre-existing antibodies from past exposure or vaccination.