Diversity in migration of CD4 and CD8 lymphocytes in different microanatomical compartments of the skin in the tuberculin reaction in man.

The lymphocytes in the perivascular foci of tuberculin skin tests have a similar CD4:CD8 ratio to those in the peripheral blood, suggesting that these subsets do not show bias in their initial emigration. By contrast, the diffusely infiltrating lymphocytes show a relative preponderance of CD4 cells which is progressively greater in successive 250 micron layers into the dermis. A generally similar pattern is seen in healthy controls and in patients with untreated pulmonary tuberculosis, treated leprosy, haemophilia A and chronic obstructive lung disease (COLD) patients treated with prednisolone, but the gradient of increasing CD4:CD8 ratio with depth into the dermis is significantly less steep in patients with tuberculosis, haemophilia and prednisolone-treated COLD than in the healthy controls. Selective migration results in a relative preponderance of CD4 cells in the diffuse infiltrate and it is suggested that this is a mechanism likely to potentiate defensive reaction to Mycobacterium tuberculosis: any deficiency in selective migration may make immunological defences less effective and so contribute to the chronicity of the lesions of tuberculosis.

The cellular responses of tuberculosis and leprosy patients and of healthy controls in skin tests to 'new tuberculin' and leprosin A.

The density and distribution of T4 and T8 lymphocytes and of monocyte/macrophages at the site of skin tests with mycobacterial antigens was studied in pulmonary tuberculosis and leprosy patients and in healthy controls. Most of the inflammatory cells were located in perivascular and periappendicular foci in the dermis: the percentage of the dermis occupied by focal infiltrate was unrelated to the clinical measurement of the area of induration. There was a less intense diffuse infiltrate in the dermis between the foci, most marked in the papillary dermis and lessening progressively in deeper layers. In patients, diffusely infiltrating lymphocytes were more numerous (mainly due to an excess of T8 cells) in relation to extracts of the pathogen causing their disease than to extracts of the other organism: T8 cells were particularly numerous in reactions to Leprosin A in three of four partly treated leprosy patients who had been classified as tuberculoid at the time of diagnosis. The density of diffusely infiltrating macrophages showed a similar density gradient and selective concentration in response to active disease pathogens. However these cells were less numerous in partly treated leprosy patients than in controls and most frequent in untreated pulmonary tuberculosis patients. Selective migration of monocyte/macrophages and, to a lesser extent T8 cells, appears to be a prominent feature in the reaction of patient with active mycobacterial disease to antigens derived from the causative organisms: this suggests that it might become possible to distinguish direct reactions from cross-reactions in human delayed hypersensitivity reactions by identification of these histological features.

Serum inhibitory factor in lepromatous leprosy: its effect on the pre-S-phase cell-cycle kinetics of mitogen-stimulated normal human lymphocytes.

The sera of ten Egyptian man with long-standing lepromatous leprosy (LL) (mean duration 17.4 years) that had failed to respond to dapsone treatment were shown to inhibit mitogen stimulation responses of normal human lymphocytes. When first tested, the sera partly inhibited the response to phytohaemagglutinin (PHA) and pokeweed mitogen and virtually abolished that to concanavalin A (Con A): after repeated freezing and thawing, the Con A inhibition had disappeared, whereas the PHA response was still partly inhibited. The inhibitory serum factor(s) had similar actions on lymphocytes from each of six normal donors. Although the sera varied in potency, they showed similar dose-response curves when tested against lymphocytes from a single donor. The principal action of the sera was to reduce the number of cells responding to mitogen, without modifying the kinetics of recruitment or rate of volume growth during G1-phase in those cells that were unaffected by the inhibitory substances(s). Study of PHA dose-response curves and of the effect of delayed addition of LL serum suggested that the serum factor(s) act by diminishing the responsiveness of the cells, rather than by reducing the concentrations of free mitogen or by blocking cell membrane mitogen receptors. The serum from one apparently healthy attendant, who had nursed leprosy patients for 30 years but who did not have leprosy or other chronic infective disease, inhibited completely stimulation by all three mitogens in a manner different from that of LL sera. Serum from the other 13 control patients did not modify the response of normal lymphocytes to stimulation by any of the three mitogens studied. It was concluded that the inhibitory factor(s) in the serum of patients with LL were a consequence of the disease and not of the environment in which the patients lived. Microscopy confirmed that the techniques used for recovery of the cultured cells did not introduce bias into the volume spectroscopy measurements.