ALTERED HELPER: SUPPRESSOR LYMPHOCYTE RATIO DURING CYTOMEGALOVIRUS INFETION OF MICE

Abstract

Cytomegalovirus (CMV) infections of humans and experimental animals have been associated with altered cell mediated immunity. In a murine model, we have observed an increased susceptibility to secondary infection during acute murine CMV (MCMV) infection. To further investigate the effect of MCMV infection upon host defense, we studied helper:suppressor lymphocyte (H:S) ratios in Balb/c mice undergoing sublethal MCMV infection. On days 1, 3, 5 and possibly 9, H:S ratios were reduced. On day 3 the H:S ratio was 0.82 in MCMV-infected mice vs 1.78 in controls (p<0.01) and on day 5, 0.59 vs 3.85 (p<0.01). On days 3 and 5, reduced H:S ratios were attributable to decreased absolute numbers of helper lymphocytes. Thereafter, suppressor cell numbers increased. Infectious MCMV was recovered from blood lymphocytes and bone marrow on days 3, 5 and 9 and from spleen on days 1 through 16.Alterations in H:S ratio appeared to correlate most closely with recovery of infectious virus trom spleen (p=0.07). Examination of bone marrow preparations suggested diminished cellularity on days 1 through 5. These results indicate that acute MCMV infection is associated with reduced H:S ratios and suggest that altered H:S ratios may correlate with enhanced susceptibility to secondary infection. These observations may be relevant to the association between CMV and opportunistic infections in human organ transplant recipients as well as in patients with the acquired immune deficiency syndrome.