Preliminary examination of lunar samples from Apollo 11: A physical, chemical, mineralogical, and biological analysis of 22 kilograms of lunar rocks and fines.

On p. 1226 the massive number of authors reported that "microscopic, culture, injection and inoculation studies on many different organisms to include mice, fish, invertebrates, insects, plants and lower animals such as parmecium, found that as of September 11, 1969, no evidence of pathogenicity has been observed."

See also: Vance I. Oyama, Edward L. Merek and Melvin P. Silverman, "A search for viable organisms in a lunar sample," Science, 167, 773-775. 
The authors found that "no viable life forms, including terrestrial contaminants, were found when the sample was tested in 300 separate environments," ending with "we conclude for this sample of the moon that there was no viable life present."

(Thanks for Juan Weiss for these references and their interpretation.)