Human natural killer-like activity against mouse spleen cells

Area of Science:

• Immunology
• Cellular Immunology
• Natural Killer Cells

Background:

• Unstimulated human peripheral lymphocytes exhibit cytotoxicity towards normal mouse spleen cells.
• These lymphocytes can suppress the in vitro antibody plaque-forming cell (PFC) response in mouse spleen cells.
• The suppressive cells share characteristics with natural killer (NK) or NK-like cells.

Purpose of the Study:

• To characterize the human lymphocyte populations responsible for suppressing the mouse PFC response.
• To investigate the mechanism by which human NK-like cells suppress the mouse PFC response.
• To evaluate the mouse spleen cell PFC system as a model for assessing human NK activity.

Main Methods:

• Assessing cytotoxicity of human lymphocytes against mouse spleen cells.
• Evaluating the effect of human lymphocytes on the in vitro PFC response to sheep red blood cells and dinitrophenylated Ficoll.
• Characterizing suppressive lymphocyte populations based on E-rosetting, adherence, surface marker expression, and cytotoxicity against K562 cells.
• Investigating the impact of effector to target cell ratios and timing of addition on PFC suppression.
• Comparing the mouse PFC system with the 51Cr-release assay for NK activity assessment.

Main Results:

• Human NK-like cells significantly suppressed the mouse PFC response, with effects observed at low effector to target cell ratios (0.67:1).
• Suppression was dependent on the timing of NK-like cell addition, with earlier addition leading to greater suppression.
• Human NK-like activity appears to suppress the mouse PFC response primarily through cell killing.
• E-rosetting T cells were found to enhance the mouse PFC response.

Conclusions:

• Human peripheral lymphocytes contain distinct cell populations that can either enhance or suppress the mouse PFC response.
• The mouse spleen cell PFC system offers a valuable model for studying human NK cell activity and the regulation of normal cellular functions.
• This model provides an alternative to traditional assays like the 51Cr-release assay for assessing NK cell function.