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2. The inbred mouse strains BALB/c and C57BL have different Ig heavy chain allotypes: The BALB/c allele is IgHa, whereas the C57BL allele is IgHb. C57BL mice make good immune responses to the antigen "Z", but BALB/c mice respond poorly. Assume you produced (BALB/c X C57Bl)F1 mice, then back-crossed these F1s to BALB/c. You tested 100 of the back-cross progeny for allotype(s) expressed in their serum, and for their ability to make anti-Z responses. The number of back-cross mice in each possible category are shown (Attached).

A second experiment was done to further examine this intriguing "responder-non-responder" phenomenon. In this experiment, T and B cells from the two strains were mixed in various combinations and stimulated with antigen Z in vitro. After three days anti-X antibody was measured. The results are shown in Table 2: (Attached)

NB: In control cultures [not shown] where no antigen was added, no responses above 10 mcg/ml were observed regardless of cell input.

What do you conclude from Table 1 about the genetic relationship of IgH and the locus controlling the responder/non-responder phenotype? Why?
What do you further conclude from Table 2? Are these results consistent with the conclusions you drew from table 1? Why/why not?

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1) What do you conclude from Table 1 about the genetic relationship of IgH and the locus controlling the responder/non-responder phenotype? Why?

OK, lets start with drawing out the crosses.

Y indicates "yes there is an anti-Z antibody made"
N indicates that "no, there is not an antibody"
a is for IgHa
b is for IgHb

So, the initial cross would be Yb X Na. If you draw out the ...

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