Are there circadian variations of polymorphonuclear phagocytosis in man?

Daily and seasonal rhythms in immune responses of splenocytes in the freshwater snake, Natrix piscator

Present study was designed to examine daily and seasonal variability in the innate immune responses of splenocytes in the fresh water snake, Natrix piscator. Animals were mildly anesthetized and spleen was aseptically isolated and processed for macrophage phagocytosis, NBT reduction, nitrite production, splenocyte proliferation and serum lysozyme activity. Samples were collected at seven time points, viz., 0000, 0400, 0800, 1200, 1600, 2000 and 0000 h during three different seasons, namely summer, winter and spring. Cosinor analysis revealed that percent phagocytosis had a significant 24-h rhythm during summer and spring seasons. The peaks of rhythms in NBT reduction and nitrite release occurred in the morning hours at 10.88 h and 8.31 h, respectively, in winter. A significant 24-h rhythm was also observed in lysozyme concentration and splenocyte proliferation (both Basal and Concanavalin A stimulated) in all three seasons. A significant phase shift in splenocyte proliferation was obtained with a trend of delayed phase shift from winter to spring and from spring to summer. Of the nine variables, significant annual (seasonal) rhythms were detected in almost all variables, excluding phagocytic and splenosomatic indices. All rhythmic variables, except spleen cellularity, exhibited tightly synchronized peaks coinciding with the progressive and recrudescence phases of annual reproductive cycle. It is concluded that the snake synchronizes its daily and seasonal immune activity with the corresponding external time cues. The enhancement of immune function coinciding with one of its crucial reproductive phases might be helping it to cope with the seasonal stressors, including abundance of pathogens, which would otherwise jeopardize the successful reproduction and eventual survival of the species.

Hypothalamic mechanisms of immunity

The present article considers a synthetical analysis of the results reported by our laboratory in the last twenty years in the field of neuroimmunomodulation. The studies we discuss here continue a previous research activity, a synthesis of which has also been published in this journal (Baciu, 1988). In that paper, we reported data concerning the role of the hypothalamic tubero-mammillary area in triggering of the phagocytic and of the secondary immune specific response. Here, we present an analysis of experimental facts gathered after 1988, and also of some prior to that date, which were not included in the above-mentioned review. They regard localizations, attained with stereotactical methods, of hypothalamic areas involved in maintenance of basal phagocytosis and of its circadian rhythm, of the phagocytic and of the primary and secondary specific response. We attempted to re-analyze these data in an integrative view, and accomplish a coherent image of the hypothalamic mechanisms of the nonspecific and specific immune response. The conclusion we draw is that the nervous system may exert its modulatory action upon the immune response in several ways: i) subsequent to a direct hypothalamic stimulation (electrical or through bacteria or bacterial products) or to a cortico-hypothalamic stimulation; ii) depending on the nature, intensity, duration, and frequency of the appropriate stimulus, it may either enhance the immune response, via neural and humoral pathways, or depress it; iii) via the hypothalamus-pituitary-adrenal axis. Nervous triggering and enhancement of the immune response are essential, their occurrence in the initial stages ensuring its favorable course. The finding that repeated electroconvulsant shocks, employed for hypothalamus stimulation in dogs of different breed, age, weight, and individual history, are followed by extremely variable changes of the phagocytic activity raises the question on the individuality of the immune response.

Sleep and the immune system

Recent animal and human studies show that the immune-neuroendocrine-thermal operations of the body are intimately linked to the sleeping-waking brain. In humans, the diurnal pattern of aspects of both peripheral cellular immune functions, e.g. natural killer cell cytotoxicity, and of cytokines, e.g. interleukin-1, are related to sleep. The harmonious interrelationships of the circadian patterns of the immune, neuroendocrine, thermal and brain functional activities are important for the cause and function of sleep. Disorganization or loss of the sleep-wake system is accompanied by alteration of the immunological, neuroendocrine and thermal functions of the body, and contributes to pathological processes such as infectious disease.

Sleep, neuroimmune and neuroendocrine functions in fibromyalgia and chronic fatigue syndrome

The justification for disordered chronobiology for fibromyalgia and chronic fatigue syndrome (CFS) is based on the following evidence: The studies on disordered sleep physiology and the symptoms of fibromyalgia and CFS; the experimental studies that draw a link between interleukin-1 (IL-1), immune-neuroendocrine-thermal systems and the sleep-wake cycle; studies and preliminary data of the inter-relationships of sleep-wakefulness, IL-1, and aspects of peripheral immune and neuroendocrine functions in healthy men and in women during differing phases of the menstrual cycle; and the observations of alterations in the immune-neuroendocrine functions of patients with fibromyalgia and CFS (Moldofsky, 1993b, d). Time series analyses of measures of the circadian pattern of the sleep-wake behavioural system, immune, neuroendocrine and temperature functions in patients with fibromyalgia and CFS should determine whether alterations of aspects of the neuro-immune-endocrine systems that accompany disordered sleep physiology result in nonrestorative sleep, pain, fatigue, cognitive and mood symptoms in patients with fibromyalgia and CFS.

Influence of circadian light-dark alternations on macrophages and lymphocytes of CBA mouse

The influence of circadian 12 h light-12 h dark alternations on CBA mouse macrophages and lymphocytes was determined using tests for macrophage spreading and ingestion ability or flow cytometry immunophenotyping of blood, lymph node, and spleen lymphocytes. The animals were tested every 4 h around the clock. Collected macrophages were incubated in vitro for 3 or 18 h. Monoclonal antibodies permitted detection of T-lymphocytes, suppressor-cytotoxic T-lymphocytes, helper-inducer T-lymphocytes, or B-lymphocytes. Two types of analyses were performed: First, the difference between the same intervals of the 12 h light or dark period was determined. The macrophage ingestion was significantly lower at the beginning and higher at the end of the dark period. We have also found a significant increase in blood T-lymphocytes of helper-inducer T-lymphocyte percentages and of the T helper-inducer: T suppressor-cytotoxic ratio during the dark period. Second, the ultradian variation during the 12 h light or dark period was determined. The variability was significant both for macrophage spreading and ingestion. Multiple significant variations of lymph node, spleen, or blood lymphocyte percentages were also observed. All of these data indicate that daily alteration of the lighting regimen significantly influences mouse peritoneal macrophage functions and various lymphocyte subsets.

Circadian variation of the phagocytic activity of polymorphonuclear leukocytes and of various other parameters in 13 healthy male adults

Twenty-four different laboratory parameters including the phagocytic activity (phagocytic index) of polymorphonuclear leukocytes (PMNs) and various hematologic variables were investigated in 13 young healthy men during Spring 1988 in Munich, Germany. Venous blood of these volunteers was obtained under standardized conditions at 4-h intervals over a 24-h span. All parameters were analyzed by the single cosinor method and by a Kruskal-Wallis analysis of variance (ANOVA). Statistically significant circadian rhythms were found for the number of circulating lymphocytes and leukocytes (WBCs), potassium, systolic blood pressure, phagocytic index, Quick test, heart rate, and rectal body temperature (p less than 0.05; single cosinor). For all of these parameters except WBCs, rectal body temperature, and Quick test, a temporal variation was confirmed by the ANOVA (p less than 0.05; phagocytic index: p = 0.05). The circadian acrophases of WBC, number of circulating lymphocytes, and phagocytic index were all found at about 01:00 h. This temporal coincidence of the acrophases of the phagocytic index and the number of circulating lymphocytes may reflect the modulation of phagocytosis by T lymphocytes that release cytokines known to stimulate the phagocytic activity of PMNs.