COMPARISON OF LYMPHOCYTE SUBSETS, MONOCYTES, AND NK-CELLS IN 3 DIFFERENT LUNG COMPARTMENTS AND PERIPHERAL-BLOOD IN THE RAT

Investigations on leukocyte populations in the lung have shown that ly mphocytes are found in different anatomical compartments. Lymphocytes can be seen to a different extent in the lung interstitium, the epithe lium and lamina propria of the bronchi, the bronchoalveolar space, and the marginal lung vascular bed. Previous studies focused on one compa rtment only, or a mixture of leukocytes from lung homogenates were pre pared. This study compared cellular yields from the lung parenchyma, t he bronchoalveolar space, and the perfusate of the lung vasculature of healthy male Lewis rats. All compartments were investigated in the sa me animal, and seven different lymphocyte subsets, monocytes, and natu ral killer (NK) cells were analyzed using flow cytometry. It was found that the perfusate contained a high proportion of CD4(+) lymphocytes compared to the lung interstitium. A very high proportion of CD4(+) ly mphocytes in the bronchoalveolar lavage (BAL) expressed markers for '' memory'' T cells. Compared to the blood, the percentage of B and T cel ls was much lower in the perfusate, whereas the NK cells and monocytes were more frequent. Analysis of leukocyte subsets within all compartm ents revealed specific, distinguishable cell compositions. Extraction of interstitial lung cells was performed using two different methods. Enzymatic digestion of the lung tissue was compared with a mechanical disruption method. Hardly any differences were observed between the tw o methods regarding the distribution of lymphocyte subsets, monocytes, and NK cells. These data document the need to study more than one com partment before extrapolating to lymphocytes in the lung in general. F urthermore, changes in numbers of leukocytes and subsets can now be st udied in models of lung infections and immune reactions, including the entry from the blood and intrapulmonary migration from one lung compa rtment to the other.