STUDIES WITH MURINE LPC-1 PLASMACYTOMA USING [6-C-14] ARGININE

[6‐14C]Arginine ([6‐14C]Arg) was used as an in vivo pulse label to study BALB/c murine LPC‐1 plasmacytoma synthesis and secretion of its tumour‐associated M component (IgG2a, k). With this isotope, an eight‐ to ten‐fold enhancement in the labelling of the γ globulin region and ten‐fold reduction in the albumin labelling were observed. Production and secretion of the M component was detected (within 30 min) after cell transfer. Only mice which received tumour cells showed significant labelling in the γ globulin region 24 hr after isotope injection. The labelling behaviour of the tumour M component correlated with the administered cell dose. The peak heights of radioactivity in the γ region increased with increments in cell number. When the percentage radioactivity diverted into M component was plotted as a function of cell dose, a linear relationship was noted. This study demonstrates the feasibility of using [6‐14C]Arg as a tool to follow the newly synthesized tumour‐associated protein, and provides a means of estimating tumour cell number. Copyright © 1979, Wiley Blackwell. All rights reserved