Immunology

See attached file for full problem description.

Table 1: Affinities of tg ARS antibodies It is possible to make transgenic (tg) mice whose B cells
___________________________________ express a tg heavy chain gene. An investigator recently Antibody Ka did an intriguing experiment to probe the basis for ___________________________________ humoral memory: She made single and double tg mice Ars11 10^-4 for two different heavy chains, that had been derived Ars55 10^-6 from previously characterized hybridomas. One, called ___________________________________ Ars-11, is a l o w affinity antibody for the paraazophenylarsonate (ARS) hapten when paired with endogenous kappa light chains; while the other, called Ars-55, has a high affinity for ARS (Table 1). Anti- idiotypic assays are available for each of these, allowing them to be individually tracked in various assay systems.

Table 2: Limiting dilution analyses of The investigaor first assessed the pre-immune
single and double tg mice frequencies of ART-reactive B cells expressing each
____________________________________ antibody in single and double tg mice (Table 2). She
Knockin Mouse Primary Frequency then immunized her double tg mice with ARS10-BSA
(per 10^5 splenic B cells) and analyzed aspects of the serum anti-ARS antibodies
_____________________ over time (Table 3). Finally, 3 months following the
Ars11 Ars55 primary immunization, she re-immunized the mice and
____________________________________ assessed their secondary responses at d5 post challenge
Single Ars11 10 0 (Table 3).
Single Ars55 0 10
Double (55 puls11) 5 5
____________________________________

Table 3: Characteristics of Ars-specific serum antibodies in double tg
mice following primary and secondary immunization
Charcteristics of Ars-specific serum antibodies
Isotype Day post ________________________________________________
Immunization Avg Total VH-11 VH-55
Ka (M) Ab (mcg) (mcg) (mcg)
0 n.d. 5 3 1
IgM 5 10^-6 155 20 130
21 10^-6 55 5 50
Secondary d5 10^-6 80 5 80
0 n.d. 3 1 1
IgG 5 10^-4 20 10 10
21 10^-8 200 175 10
Secondary d5 10^-8 600 550 10

1) What do you conclude from the data given in Table 2? Why was it important for the investigator
to do this experiment?

2) What do you conclude from the information about the primary response given in table 3?;

3) What do you conclude from the information given about the memory response in Table 3?

4) Advance a hypothesis that would explain these data and briefly outline an experiment that
would test one aspect of your hypothesis.