Relationship between large granular lymphocytes and NK-1.2+ cells from normal and poly(inosinic:cytidylic acid) (poly(I:C]-treated mice.

The present work analyzes the relationship between large granular lymphocytes (LGL), NK-1.2+ cells, and natural killer (NK) activity of C3H/HeN mice. Different hematic cell fractions were obtained according to their nylon-wool adherence and density on Percoll gradients. NK-1.2+ cells (8% of nucleated cells) were more numerous than LGL (3% of nucleated cells) in the input blood population. Eighty-five percent of LGL were recovered from the sorted NK-1.2+ cell fraction. After incubation on nylon-wool column, 63% of LGL and 36% of NK-1.2+ were eluted in the nonadherent fraction. Eighteen percent of NK-1.2+ cells were recovered from the most adherent elutable cell fraction. After the discontinuous Percoll gradient most LGL were present in the low-density fractions while 20% of NK-1.2+ cells were recovered from the highest-density fraction. NK activity was significant both in the nylon-wool-nonadherent and -adherent fractions. After the Percoll gradient most NK activity was present in the low-density fractions. In the present experimental conditions treatment poly(inosinic:cytidylic acid) (poly(I:C] did not increase the numbers of LGL and NK-1.2+ cells either in the blood or in the spleen. However it increased significantly the NK activity of the input cell populations and of the nonadherent and low-density fractions. Similarly, exposure of specific pathogen-free (SPF) mice to non-SPF conditions stimulated NK cytotoxicity but did not alter the percentage of LGL in the blood or in the spleen. Poly(I:C) treatment induced a shift of LGL and NK-1.2+ cells toward the low-density fractions. In poly(I:C)-treated mice images of granule secretion from LGL were detected. Taken together, the present results indicate that LGL and NK-1.2+ cell populations do not totally overlap. Moreover subpopulations of LGL and NK-1.2+ cells can differ in NK activity, morphology, density, adherence to nylon wool, and response to poly(I:C).