You will be given a definition of a task first, then some input of the task.
Given a passage, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.

We assessed the expression of natural killer (NK) receptors in recurrent aborters before and after immunotherapy using their husbands' peripheral blood mononuclear cells (PBMCs).", 'Using stored PBMCs from recurrent aborters before and after the immunotherapy, the expression of NK receptors, CD158a, CD158b, CD159 and CD94, were analyzed using monoclonal antibodies for respective receptors. The diversity of killer activatory receptors (KARs) and killer inhibitory receptors (KIRs) was also examined using reverse transcriptase-polymerase chain reaction (RT-PCR)-single strand conformation polymorphism (SSCP) method.', 'In recurrent aborters, no apparent changes in NK receptor expression and the balance between KARs and KIRs were found before and after the immunotherapy.
Output:
Does immunotherapy prevent recurrent abortion without influencing natural killer receptor status?