Early Blood Leucocyte Changes in Mice and Guinea Pigs Following X‐Irradiation and Stress Caused by Operative Manipulations

Rapid shifts in the relative frequencies of the white cells of animals may occur following injection e. g. of toxins or other agents, radiation, but even mechanical manipulations (J acobson 1954, C raddock 1960). The present work demonstrates the complexity of the reactions and the species differences between mice and guinea pigs following X‐radiation and the manipulations (sham irradiation). A detailed survey (Table I‐III) shows, that in mice eosinophils decrease following sham and X‐radiation, that monocytes fall significantly by sham treatment but not furtheron after radiation, that rods increase continuously in number by application of sham treatment and X‐rays. In these and other respects guinea pigs show a different behaviour, bearing witness to the multiformity of the reactions. Leucocytes in general are apt to be released into the circulation from myeloid marrow at short notice. The capillary beds of various tissues seems to afford another reservoir (H arris 1959, O sgood 1954). The highly differentiated mode of reaction of the various leucocytes and the species differences is however not easily accounted for on the notion of a simple mechanism regulating the flow to and from the circulating blood. The habitual action of ionizing radiation on the white cell picture of the circulating blood is that of causing a general concentration fall, which becomes manifest some 6–8 hours post‐irradiation. The magnitude and duration of this decrease is dose dependant and may serve as an indication of a radiation influence of the organism in practice. Foregoing this stage a period of very rapid concentration changes during the first hours was noticed by many workers, although detailed analyses do not seem to have been performed. On the other hand the white cells are very motile and a flow to and from the circulation is caused by a variety of measures including injections of chemicals, hormones among others. It may well be that the irradiation effects are mediated through release of some such substances. The complexity of the early white cell reactions was realised from our preliminary trials, and particularly the species differences between mice and guinea pigs. This induced us to a general survey of the early radiation reactions, including also the simultaneous stress effects caused by the mechnical manipulations of the animals.