Expression of Bruton's agammaglobulinemia tyrosine kinase gene, BTK, is selectively down-regulated in T lymphocytes and plasma cells

J Immunol. 1994 Jan 15;152(2):557-65.


The gene mutated in the human disease, X-linked agammaglobulinemia (XLA), is related to the Src gene family of cytoplasmic protein-tyrosine kinases and is designated Btk (Bruton's agammaglobulinemia tyrosine kinase; formerly Atk/Bpk; the human gene is denoted BTK, using capital letters according to the kinase nomenclature). We have recently reported that this gene is expressed in B lymphocytes and that the specific mRNA was undetectable in T cells using Northern blotting. Further analyses of different sources of B and T lymphocytes confirmed this pattern. However, BTK transcripts were undetectable in four plasmacytoma lines. Moreover, as virtually normal amounts of BTK transcripts were found in PBMC from two patients carrying a point mutation in BTK, despite low B cell numbers, we anticipated that the gene would also be expressed in cells of other lineages. The erythroleukemia cell line K-562, the promyelocytic line HL-60 and the histiocytic lymphoma line U-937 were found to have BTK mRNA levels comparable to B cells. BTK mRNA was also detected in monocytes from healthy donors as well as in the human immature basophilic cell line KU812, in the human mast cell leukemia cell line HMC-1 and in the CD34 expressing myeloblast KG-1. A similar expression pattern was obtained when BTK protein was analyzed by immunoprecipitation and Western blotting. Using a polymerase chain reaction-based analysis, a small amount (less than 1% of the level in B cells) of BTK mRNA was identified in T lymphocytes. Our findings are compatible with a general expression of the BTK gene in hematopoietic cells, except in T lymphocytes and plasma cells, in which the transcript level is selectively down-regulated.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Agammaglobulinemia / enzymology*
  • B-Lymphocytes / cytology
  • B-Lymphocytes / enzymology
  • Base Sequence
  • Bone Marrow / enzymology
  • Cell Differentiation
  • DNA Primers / chemistry
  • Gene Expression / drug effects
  • Humans
  • Mast Cells / enzymology
  • Molecular Sequence Data
  • Phorbol Esters / pharmacology
  • Plasma Cells / enzymology*
  • Protein-Tyrosine Kinases / metabolism*
  • RNA, Messenger / genetics
  • T-Lymphocytes / enzymology*
  • Tretinoin / pharmacology
  • X Chromosome


  • DNA Primers
  • Phorbol Esters
  • RNA, Messenger
  • Tretinoin
  • Protein-Tyrosine Kinases