The Spontaneous Release of ⁵¹Cr from Labeled EL-4 Ascitic Lymphoma Cells as Dependent Upon the Composition of the Cell Population

Abstract

Investigations on the spontaneous release of stCr from the EL-4 ascitic lymphoma showed that daily rhythmic changes can be correlated with the dominance of certain cell types in the population. A generation time of 9.8 h, an average doubling time of 32 h, and an ‘appearance cycle’ of 96 h were established for the population. Earlier observed variations in the values for spontaneous ⁵¹Cr release can be explained in terms of the cellular composition of the population.

Dependence of Cell-Mediated Immune Lysis of the EL-4 Ascitic Lymphoma on Its Population Composition and Rhythm

“…Lastly, our contention, presented in our previous publication [3], that considerable differences in immune lysis might result from variations in population composition, under otherwise identical experimental condi tions, has been borne out in the present study. A comparison of the final results of immune lysis, as compiled in table I, shows that the variation, depending upon the population rhythm, is from 13.5 to 52.5%, i.e., > 3 0 0 % .…”

“…On the other hand, when Q2 cells reenter the reproductive cycle, they will undergo mitosis once, giving rise to two indetermined early G, forms, thus increasing the proportion of vulnerable cells in compartment 1. In our previous study [3], it has been shown that compartments 3 and 4 (composed of D and Sn cells, respectively) are primarily responsible for the spontaneous release of 51Cr; therefore, it is not surprising that on days when these D and Sn cells dominate the population, immune lysis will be relatively slight, in comparison to those days when compartments 1 or 2 are in dominance.…”

“…In a previous paper investigating the spontaneous release of 5,Cr from EL-4 ascitic lymphoma cells, we found that daily rhythmic changes can be correlated with the dominance of certain cell types in the population [3], Microscopic investigations of the ascitic tumors revealed that one can distinguish four cellular compartments on the basis of cell morphol ogy. Compartment 1 is made up of stem cells, which are uniformly small with dense nuclear material, excepting those clearly in telophase.…”

“…Table I presents a comparison of background lysis and immune lysis with the percentages of cells in compartment 1, according to their daily rhythms. The cell percentages represent averages of counts from three series of 4 days, all performed in quadruplicate (for details, see the methodology in De Bernardo et al [3]). The determinations on lysis are the results of two experiments, each in triplicate.…”

Natural Cytotoxicity against Chemically Induced Neurogenic Rat Tumors

“…Percent background release varied some what with each experiment possibly due to changes in cell cycle [9], Despite this varia- tion, the levels of background release for the attached labeled cells during a 24-hour incu bation period permitted its application in a long-term 24-hour assay for these tumor cell lines.…”