I have a data analysis immunobiology question I need some help with: Here is som

Question

I have a data analysis immunobiology question I need some help with:

Here is some background information:

When C57BL mice are immunized with the haptennitrophenacetyl (NP) on a suitable carrier, they makea robust response, with germinal centers waxing andwaning over a 21-day period as antigen is cleared. This is a nice model because (1) the response iscomprised mainly of B cells expressing a VH genecalled 81X paired with a lambda light chain; and (2)in secondary responses, the amino acid at position94 in the heavy chain has been replaced by atyrosine, lending higher affinity than the unmutatedheavy chain. Thus, by using FACS with acombination of reagents to track memory B cellmarkers, NP-binding, and lambda light chainexpression, one can detect and sort memory cellpopulations, then perform single cell PCR to analyzeV-region sequences. In an effort to understand thegeneration and dynamics of memory B cells, aninvestigator immunized C57BL mice once with NP. He then determined the total number of memory Bcells in the spleen and the proportion of memorycells with the tyr-94 mutation at varying times afterimmunization.

The data for this experiment is below:

Here is the question I need some help with:

1a. Advance a mechanistic hypothesis about the establishment and maintenance of memory B cells that could accommodate all of these findings.

1b. Outline one experiment that would test the validity of at least one aspect of your hypothesis.

Explanation / Answer

B lymphocytes are produced from the red bone marrow and are mainly involved in providing antibody mediated immunity. When these cells encounter the presence of a specific antigen, then become activated or sensitized. In the subsequent processes, the antigens bound to the class II MHC proteins (major histocompatibility complex) present on B cell surface.

The same antigen also activates helper T cells; these T cells bind to the MHC of the activated B cell. This step helps in recognizing the antigen, and the helper T cells start secreting the cytokines that stimulate activation of B cells.

Under the stimulation of cytokines, B cells differentiate into plasma cells that are capable of secreting antibody molecules about 100 million per hour (per each plasma cell) and memory cells that can memorize the pathogenic antigens and elicit antibody production if the subject is infected with the same antigen.

1A)

The hypothesis regarding the establishment and maintenance of NP specific memory B cells is that the mutated cells B-cells have low rate of expression, so they are expressed several weeks after immunization. But eventually, they are expressed to high level.

1b)

The experiment to test the expression of specific memory B cells is induction of new mutations in the genes that are specific NP-B cells and check the pattern of expression after immunization.

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