The literature contains little descriptive information about the origin of McCoy cells. They were first mentioned by Pomerat, et al. (Z. Zellforsch. 47: 158-174, 1957). The cells were reported to have originated from the synovial fluid in the knee joint of a patient suffering from degenerative arthritis, and in 1965 Defendi, et al. showed that McCoy cells (designated McCoy A) were indeed human cells. However, another subline (designated McCoy B) was found to be of mouse origin and possessed marker chromosomes characteristic of strain L mouse fibroblasts. McCoy cells presumed to be human, but which were in fact mouse cells, have been disseminated from laboratory to laboratory throughout the world. Initial interest in McCoy cells followed demonstration by Gordan and Quan (Proc. Soc. Exp. Biol. Med. 118: 354-359, 1965) and Gordon, et al. (Appl. Microbiol. 23: 123-129, 1972) that ionizing radiation (cobalt-60) greatly increased the susceptibility of McCoy cells to infection by chlamydia strains. In 1984 the Cell Culture Department of the Centers for Disease Control in Atlanta, Georgia, received a culture of the so-called McCoy cell line. Documentation as to origin or passage history was unavailable. The cells have been used to propagate laboratory strains of the 15 recognized serotypes of Chlamydia trachomatis, and the cell line has been satisfactory for chlamydia growth for least 43 passages at ATCC.

Culture Medium
Minimum essential medium (Eagle), with 10% heat-inactivated fetal bovine serum.

Growth Characteristics
Cells seeded at a concentration of 2x10⁴ cells/cm² in the above culture medium will be 100% confluent in 5 days.

Morphology
Fibroblast-like.

Common Utilization
Isolation of Chlamydia trachomatis.