Factors Influencing the Isolation of Membrane Immunoglobulins from T and B Lymphocytes

[摘要] The optimal conditions for the extraction and isolation of immunoglobulins from the cell membrane (M-Ig) of T and B lymphocytes radioiodinated with lactoperoxidase were studied. A combination of 10 M-urea, 1.5 M acetic acid and the non-ionic detergents Triton X-100 or Nonidet P-40 (NP-40) was found to overcome the tendency for membrane proteins to precipitate after extraction in urea-acetic acid alone. However, detection of T cell Ig was more dependent on detergent concentration than B cell M-Ig. Less T cell Ig was detected when the detergent concentration was increased from 0.1% to 1.0%, whereas the amount of B cell M-Ig was not affected by higher detergent concentrations. All polyvalent and anti-κ-chain antisera tested reacted with T and B cell M-Ig, however, anti-µ-chain sera bound B cell M-Ig only. Disc electrophoresis (PAGE) of reduced and alkylated T M-Ig revealed polypeptide chains with mobilities of Ig µ and L chains and additional polypeptides with apparent m.w. of 45,000 and 30,000. The latter two polypeptides were present in nonspecific precipitates also. PAGE analysis of B cell M-Ig revealed µ-chains, a second heavy chain with an apparent m.w. of 65,000 as well as L chains, and, in addition, polypeptides with apparent m.w. of 45,000 and 30,000.It is suggested that T cell immunoglobulin is structurally distinct from B cell membrane Ig and may share some properties characteristic of integral membrane proteins.

[学科分类] 生物科学（综合）