What is the lymphocyte phenotype associated with SCID caused by an Artemis defect?

The lymphocyte phenotype associated with Severe Combined Immunodeficiency (SCID) resulting from an Artemis defect is characterized by the presence of NK cells, while T and B cells are absent. This unique profile, known as T-B-NK+, indicates that there are no functional T lymphocytes and B lymphocytes, but there are natural killer (NK) cells present.

This phenotype is specifically seen in some types of SCID due to genetic defects that affect the development of T and B lymphocytes, such as those caused by mutations in the Artemis gene. Artemis is critical for the V(D)J recombination process, which is essential for the generation of diverse T and B cell receptors. Without functional T and B cells, the immune system cannot effectively respond to infections, while the presence of NK cells can be noted, indicating that at least some aspect of the innate immune response remains intact.

The other options reflect various combinations of T, B, and NK cell presence or absence that do not align with the specific phenotype associated with an Artemis defect. For instance, the presence of B cells or the absence of NK cells is not characteristic of Artemis-related SCID. Thus, T-B-NK+ is the correct representation of the lymphocyte phenotype in this particular