Interleukin-7R alpha mRNA expression increases as stem cells differentiate into T and B lymphocyte progenitors

Area of Science:

• Immunology
• Molecular Biology
• Developmental Biology

Background:

• The gamma common (gamma c) chain is a key component of interleukin receptors, including IL-2R, IL-4R, and IL-7R.
• Mutations in the gamma c gene are linked to X-linked severe combined immunodeficiency (SCID).

Purpose of the Study:

• To investigate the expression of gamma c and its partners in mouse pluripotent hematopoietic stem cells (PHSCs) and developing lymphocytes.
• To determine when interleukin receptor (IL-R) complexes are expressed during early T and B lymphocyte maturation.

Main Methods:

• Reverse transcriptase-polymerase chain reaction (RT-PCR) was used to analyze mRNA levels.
• Expression of gamma c and IL-7R alpha mRNA was examined in PHSCs and various stages of T and B lymphocytes.

Main Results:

• Pluripotent hematopoietic stem cells (PHSCs) lacked detectable IL-7R alpha mRNA.
• Primitive T and B lymphocytes expressed high levels of IL-7R alpha mRNA.
• Gamma c mRNA levels were consistent across PHSCs and developing lymphocytes.

Conclusions:

• Interleukin-7 receptor (IL-7R) expression begins at the earliest stages of T and B lymphocyte differentiation.
• The lack of a complete IL-7R complex (IL-7R alpha and gamma c) is critical for lymphopoiesis and may cause SCID.