LSAT 111 – Section 4 – Question 22

LSAT 111 - Section 4 - Question 22

October 2001

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Question QuickView	Type	Tags	Answer Choices	Curve	Question Difficulty	Psg/Game/S Difficulty	Explanation
PT111 S4 Q22	+LR	Miscellaneous +Misc Must be false +MBF Causal Reasoning +CausR	A 72% 167 B 10% 160 C 6% 160 D 8% 159 E 4% 161	147 156 166	+Harder	144.86 +SubsectionEasier

J.Y.’s explanation

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Multiple sclerosis is an autoimmune disease: white blood cells attack the myelin sheath that protects nerve fibers in the spinal cord and brain. Medical science now has a drug that can be used to successfully treat multiple sclerosis, but the path that led medical researchers to this drug was hardly straightforward. Initially, some scientists believed attacks characteristic of multiple sclerosis might be triggered by chronic viral infections. So in 1984 they began testing gamma interferon, one of the body’s own antiviral weapons. To their horror, all the multiple sclerosis patients tested became dramatically worse. The false step proved to be instructive however.

Summary

Scientists thought multiple sclerosis (MS) was caused by viral infections. To test this hypothesis, they used gamma interferon—a tool the body uses to combat viral infections—to treat MS. This experiment, however, resulted in the MS patients’ conditions worsening.

Notable Valid Inferences

Gamma interferon makes MS worse.

Gamma interferon stops white blood cells from producing myelin-destroying compounds.

This is not compatible with the experiment’s results. If gamma interferon does what (A) claims, it would interfere with the mechanism that makes MS so destructive. This would likely improve MS patients’ conditions—this contradicts the experiment, which shows the opposite effect.

Administering gamma interferon to those without multiple sclerosis causes an increase in the number of white blood cells.

This could be true and may explain why gamma interferon makes MS patients’ conditions worse. By causing an increase in white blood cells, gamma interferon could increase the number of cells attacking the myelin sheath in MS patients.

Medical researchers have discovered that the gamma interferon level in the cerebrospinal fluid skyrockets just before and during multiple sclerosis attacks.

This could be true and may explain why gamma interferon makes MS patients’ conditions worse. It suggests an association between increased gamma interferon levels and MS attacks.

It has now been established that most multiple sclerosis sufferers do not have chronic viral infections.

This could be true. It suggests that scientists’ initial belief that MS is triggered by viral infections is incorrect. This could explain why gamma interferon, one of the body’s antiviral tools, is ineffective against it.

The drug now used to treat multiple sclerosis is known to inhibit the activity of gamma interferon.

This could be true and may explain why gamma interferon makes MS patients’ conditions worse. It suggests that inhibiting gamma interferon levels improves patients’ conditions—this is consistent with the finding that increasing gamma interferon levels worsens patients’ conditions.

LSAT 111 – Section 4 – Question 22

LSAT 111 - Section 4 - Question 22

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J.Y.’s explanation

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LSAT PrepTest 111 Explanations

Section 1 - Logical Reasoning

Section 2 - Reading Comprehension

Section 3 - Logical Reasoning

Section 4 - Logical Reasoning

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