A Child Who Suffers from a Persistent Viral Infection Is

question 9

Multiple Choice

A child who suffers from a persistent viral infection is found to have a deficiency in lymphocyte production and very few T and B cells.Other bone marrow-derived cells are produced in normal numbers,and MHC molecule expression on cells appears normal.Transfusion of mature T cells from an unrelated donor who had recovered from a previous infection by the same virus would not be expected to help the child clear his infection.Which one of the following is a reasonable explanation for why this therapeutic approach would fail?

• A)Viral infections are cleared by antibodies,not T cells.
• B)The patient's own immune system would destroy the transfused T cells before they could respond to the viral infection.
• C)T cells recognize peptides,not viral particles.
• D)Donor T cell viral antigen recognition is restricted by MHC molecules not expressed in the patient.
• E)In responding to the previous infection,the donor would have used up all his T cells specific for that virus.

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Definitions:

Invoice

A document detailing a transaction between a buyer and seller, including the quantity, price, and terms of sale.

Cash Discount

A deduction from the invoice price offered by a seller to encourage prompt payment by the buyer.

Payment Terms

The conditions under which a seller will complete a sale, typically specifying the period allowed to a buyer to pay off the amount due.

Invoice

A document issued by a seller to a buyer indicating the products or services provided, their quantities, and the agreed prices for products or services the seller has provided but not yet been paid for.