Question XIII Consider each numbered statement 136140 concer

Question XIII. Consider each numbered statement (136-140) concerning various immunological facts, concepts and terminology as a completely independent assertion. Using your knowledge, please, assess these statements as factually correct (= true, T) or incorrect (= false, F):

136. The 12/23 rule means that a diversity (D) segment is almost always included in the formation of the immunoglobulin heavy-chain V region.

137. In generating a B-cell receptor gene, Vk segments sometimes join to Cl segments.

138. In generating a T-cell receptor gene, Va segments sometimes join to Cd segments.

139. The switch in constant region usage from IgM to another immunoglobulin class (= isotype switching) is always mediated by DNA rearrangements.

140. A major reason why one individual might mount a response against a specific self-peptide, while other individuals might not is that there are differences in peptide binding potential of different MHC molecules

Solution

136. True, the 12/23 rule means that a diversity (D) segment is almost always included in the formation of the immunoglobulin heavy-chain V region.

137. False. In generating a B-cell receptor gene, Vk segments do not join to Cl segments.

138. False. In generating a T-cell receptor gene, Va segments do not join to Cd segments.

139. True. isotype switching) is always mediated by DNA rearrangements.

140. True