LSAT Explanation PT 35, S4, Q22: Multiple sclerosis is an autoimmune disease:

LSAT Question Stem

Which one of the following is LEAST compatible with the results of the gamma interferon experiment? 

Logical Reasoning Question Type

This is a Must Be False question. 

Correct Answer

The correct answer to this question is A. 

LSAT Question Complete Explanation

This question is an "inference (must be false)" question, which asks you to identify the answer choice that is least compatible with the information provided in the passage. In other words, the correct answer will be the one that is contradicted by the information in the passage. Let's briefly analyze each answer choice in light of the passage:

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

The passage tells us that when multiple sclerosis patients were tested with gamma interferon, their condition became dramatically worse. This suggests that gamma interferon does not stop white blood cells from producing myelin-destroying compounds, as doing so would have improved the patients' conditions. Therefore, this answer choice is least compatible with the passage and is the correct answer.

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

This answer choice discusses the effect of gamma interferon on people without multiple sclerosis, which is not addressed in the passage. Since we cannot determine whether this statement is true or false based on the information provided, it is not the least compatible answer choice.

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

While the passage does not specifically mention this discovery, it does not contradict the information provided. Thus, this answer choice is not the least compatible with the passage.

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

The passage states that scientists initially believed multiple sclerosis attacks might be triggered by chronic viral infections, but the gamma interferon experiment proved otherwise. This answer choice is in line with the passage and is not the least compatible option.

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

Since gamma interferon made multiple sclerosis patients' conditions worse, it is reasonable to think that a drug that successfully treats multiple sclerosis might inhibit the activity of gamma interferon. This answer choice is not contradicted by the passage and is not the least compatible option.

In conclusion, the correct answer is (a) because it is least compatible with the information provided in the passage. The other answer choices are either compatible with the passage or cannot be determined based on the information provided.