LYMPHOCYTE PROFILES IN PATIENTS WITH CHRONIC LOW-BACK-PAIN ENROLLED IN A CLINICAL-TRIAL

Objective: Our earlier findings suggest that patients with musculoskel etal complaints have lower numbers and percentages of natural killer ( NK) cells than asymptomatic subjects. This study examines patient lymp hocyte profiles, as a secondary outcome measure, in a trial of manipul ative therapies to treat chronic low back pain (LBP) of mechanical ori gin. Design: The patients were compared in a randomized controlled tri al. Baseline measures were collected at the initial visit; all patient s were scheduled for 11 treatments in 14 days. Treatment consisted of either a high-force, high-velocity, low-amplitude manipulation procedu re; a low-force, high-velocity, low-amplitude procedure or a series of educational lectures on lower back pain. Posttreatment measures were collected at the final treatment session; follow-up measures were obta ined 2 wk later. Setting: The study was conducted at a chiropractic te aching clinic in the suburban Chicago area. Participants: Individuals over 18 were eligible if they were new patients or repeat patients wit h a 6 month's hiatus, if the chief complaint was LBP of greater than 5 0 days' duration, if pain was elicited with palpation over one or more of the facet joints from the spinal levels between L1 and S1 and incl uding the sacroiliac joints, and if there was absence of pain referral or if pain referral was only scleratogenous in nature. Criteria for e xcluding patients included hard neurologic signs, systemic disease pot entially affecting the musculoskeletal system, contraindication to spi nal manipulation such as osteoporosis, fracture or other bony patholog y, or treatment with medication intended to relieve symptoms associate d with their LBP. Eligibility was determined by a staff diagnostic tea m independent of the attending physician. Three hundred sixty-seven of 1,275 consecutive new patients met the eligibility criteria. Of these , 209 participated. These results are for 201 patients from whom flow cytometric data were obtained. Outcome Measures: Both absolute numbers and percentages of B-lymphocytes, T-lymphocytes, T-Helper (T(H)), T-S uppressor (T(S)) and NK lymphocytes were determined. Blood samples wer e collected at the same time that the primary outcome measures were ob tained. Cells were stained with two-color monoclonal antibodies direct ed against specific cell surface antigens, and each lymphocyte subpopu lation was quantified directly from lysed whole blood with a Coulter E pics Profile II flow cytometer. Results: Thirty-five patients dropped out before the follow-up visit and technical problems resulted in the loss of data from 17 more and the exclusion of some subpopulation data . In all, 148 cases were analyzed for B cells, 146 for T(H), T(S) and NK cells and 138 for cells that carried both the NK and T(S) marker. A one-way analysis of variance revealed no significant differences in t he lymphocyte profiles at baseline among the three groups. All subpopu lation baseline values were within reported reference ranges for norma l adult populations. However, the percentage of NK cells (9.1%) was be low the published minimum critical value. A repeated measures analysis of variance was used to determine whether treatment effects changed o ver time, that is, treatment-time interaction. The cell types for whic h the interaction tests were at or near statistical significance were: T(H) cells (p = .0208), total T cell percent (p = .0928) and absolute total T cells (p = .0908). Interaction tests for differences in eithe r percent or absolute counts of B cells, T(s) cells, or NK cells were not statistically significant. Conclusions: This is the first report o f lymphocyte profiles in patients with diagnosed chronic LBP. Our find ing of a lower percentage of NK cells in these patients confirms our e arlier finding that patients with musculoskeletal problems have a lowe r percentage of NK cells than do asymptomatic subjects. However, manip ulative therapy was not shown to have a clinically significant effect on either the absolute number or percentage of any lymphocyte subpopul ation studied. Because lymphocyte profiles were a secondary outcome in this trial, the eligibility criteria established for the primary outc omes may not have been rigorous enough to avoid confounding these resu lts or the treatment schedule or sampling times may not have been appr opriate to detect changes at the cellular level.